929 (Tanakh)

I Samuel 20

StandardAugust 17, 2026

Sugya Map & Snapshot

The narrative of David’s flight from Saul’s court, culminating in his dramatic covenantal parting from Jonathan in I Samuel 20, serves as the locus classicus for analyzing the intersection of political loyalty, familial obligation, and the halakhic definitions of mortal danger. The sugya presents a complex web of legal and psychological tensions, which can be mapped through three distinct inquiries:

  • The Halakhic Status of the Pursued (Nifrad vs. Rodef): At what point does a sovereign’s erratic hostility elevate his status from a monarch exercising judicial prerogative to an objective pursuer (rodef) whom one is obligated to escape or neutralize?
  • The Jurisprudential Mechanics of the Covenant (B'rit): Does the oath (shevuah) between David and Jonathan constitute a bilateral partnership (shutfut) with reciprocal liabilities, or is it a unilateral act of grace (chesed) that suspends standard filial obligations (kibbud av)?
  • The Spatial-Spiritual Dimension of Naioth (Naioth/Nayot): Is David’s refuge in Naioth in Ramah a purely tactical retreat, or does it represent a metaphysical sanctuary of Torah study that temporarily immunizes him from political prosecution?

Nafka Mina (Practical Halakhic Ramifications)

  1. The Shoteh (Insane Person) as a Rodef: If Saul's homicidal mania is classified as temporary insanity (ruach ra'ah), does he retain the status of a king whose commands must be obeyed, or does his lack of da'at (cognitive competence) strip him of royal immunity, rendering him a classic rodef under the guidelines of Sanhedrin 72a?
  2. Conflict of Halakhic Obligations: Is Jonathan halakhically permitted to actively deceive his father to save his friend, or does the biblical mandate of kibbud av Exodus 20:12 restrict him to passive non-cooperation?
  3. The Validity of Oaths Under Duress (Ones): Does Jonathan’s covenantal oath to protect David’s lineage remain binding if it constitutes high treason against the reigning dynasty, potentially invoking the status of an oath made under duress (shevuat onsin) under Shevuot 26a?

Text Snapshot

Let us examine the opening verse of our chapter:

"וַיִּבְרַח דָּוִד מִנָּוֺת [מִנָּיֺת] בָּרָמָה וַיָּבֹא וַיֹּאמֶר לִפְנֵי יְהוֹנָתָן מֶה עָשִׂיתִי מֶה־עֲוֺנִי וּמֶה־חַטָּאתִי לִפְנֵי אָבִיךָ כִּי מְבַקֵּשׁ אֶת־נַפְשִֽׁי׃" — I Samuel 20:1

This verse contains a critical Keri/Ketiv anomaly regarding the word Naioth. The text is written (Ketiv) as מִנָּוֺת (from Navot, implying physical dwellings or pastures from the root naveh), but read (Keri) as מִנָּיֺת (from Nayot, implying plural beauties or spiritual eminences).

Furthermore, David’s plea to Jonathan utilizes a precise tripartite legal taxonomy: meh asiti (what have I done?), meh avoni (what is my iniquity?), and meh chattati (what is my sin?). This is not mere poetic parallel; as we shall see, it is a highly structured forensic defense designed to systematically eliminate any legal justification for Saul's pursuit.


Readings

To unpack the layers of this text, we must analyze the classical commentaries, tracing how their textual emendations reveal deeper conceptual undercurrents.

1. The Timing of the Flight: Radak, Metzudat David, and Malbim

The text begins: "David fled from Naioth in Ramah" I Samuel 20:1. The commentators are troubled by the timing of this flight. In the preceding chapter, Saul had sent messengers to seize David, but they, and eventually Saul himself, were overcome by prophetic ecstasy, stripping off their clothes and lying down naked all that day and night I Samuel 19:20-24.

The Radak writes:

"ויברח דוד. בעוד שהיה מתנבא שאול ברח לו" "David fled: While Saul was prophesying, he fled for himself." [^1]

Similarly, the Metzudat David notes:

"ויברח. בעוד שאול מתנבא, ברח ובא לביתו" "He fled: While Saul was prophesying, he fled and came to his house." [^2]

And the Malbim refines this observation:

"ויברח בעוד התנבא שאול היה לו זמן לברוח" "He fled: While Saul was prophesying, he had time to flee." [^3]

The Conceptual Inquiry (Chakirah)

These comments point to a profound chakirah regarding the nature of Saul’s prophetic state. Was Saul's ecstatic paralysis a supernatural physical restraint, or was it a temporary suspension of his legal and psychological agency?

If we adopt the Radak’s view that David fled "while Saul was prophesying," we must ask why this was the chosen moment. The Malbim answers that this state of prophecy provided a literal "window of time" (had lo zman livroach).

In the realm of lomdus (conceptual analysis), we can analyze this through the lens of Maimonides’ definition of prophetic ecstasy. In Hilkhot Yesodei HaTorah 7:2, the Rambam states that during prophecy, a prophet’s physical senses are neutralized and his limbs tremble. Thus, Saul was physically and cognitively incapacitated.

David did not merely escape a tyrant; he exploited a divinely mandated suspension of Saul’s royal agency. While Saul was stripped of his clothing and his royal dignity—symbolizing the temporary abdication of his monarchy—David reclaimed his mobility. The flight from Naioth was not a cowardly retreat, but a strategic exit executed during a period when the pursuer was legally and physically "non-functional."

                       [Saul's Prophetic Ecstasy]
                                   |
                  +----------------+----------------+
                  |                                 |
         [Physical Restraint]             [Suspension of Agency]
         - Limbs paralyzed                - Royal authority paused
         - Sensory shutdown               - "Da'at" temporarily absent
                  |                                 |
                  +----------------+----------------+
                                   |
                       [David's Window of Flight]

2. David’s Forensic Defense: Malbim on the Tripartite Plea

When David reaches Jonathan, he asks: "What have I done? What is my iniquity? and what is my sin before your father, that he seeks my life?" I Samuel 20:1.

The Malbim parses these terms with surgical precision:

"מה עשיתי רצה לומר מה חטאתי בפני עצמי או מה עוני כו' לפני אביך בחטא הנוגע למלכות" "'What have I done'—meaning: what did I sin against myself, or what is my iniquity etc. before your father in a sin relating to the kingdom?" [^4]

The Malbim divides David's three questions into distinct legal domains:

Term Legal Domain Definition Halakhic Parallel
מֶה עָשִׂיתִי (Meh Asiti) Personal Conduct Direct, objective harm against another individual. Bein Adam LeChavero (Civil Tort)
מֶה־עֲוֺנִי (Meh Avoni) Political Treason Intentional rebellion against the crown (mored be-malchut). Hilkhot Melakhim 3:8
וּמֶה־חַטָּאתִי (U-meh Chattati) Unintentional/Relational Unintentional slights or ritual failures that offend the king's honor. Shifgal/Shogeg (Negligence)

By utilizing this tripartite division, David is setting up a comprehensive forensic defense. He challenges Jonathan to produce an indictment in any of these three categories:

  1. If Saul is pursuing him for a civil crime (meh asiti), where is the victim?
  2. If Saul is pursuing him for treason (meh avoni), where is the evidence of a conspiracy to usurp the throne?
  3. If Saul is pursuing him for an accidental protocol breach (meh chattati), such a minor infraction cannot justify a capital sentence.

In the language of the Talmudic courts, David is demanding a formal Shtar Chov (bill of indictment). He argues that because there is no legal basis for his execution, Saul's pursuit is entirely extrajudicial, stripping Saul of his royal privilege and transforming him into a common murderer.

3. The Orthographic Mystery of "Naioth": Minchat Shai and Eruvin

The Minchat Shai notes the orthographic variation in I Samuel 20:1:

"מנוות. מניות קרי" "From Naioth (written מנוות): Read as Nayot (מניות)." [^5]

To understand the conceptual weight of this textual variance, we must turn to the Talmudic discussion in Eruvin 18b:

"מאי חנוות [מניות] ברמה? אמר רבי יוחנן: שהיו יושבין ברמה ועוסקין בנויו של עולם." "What is Naioth in Ramah? Rabbi Yochanan said: They were sitting in Ramah and occupying themselves with the beauty (noy) of the world [the study of the Temple’s location]." [^6]

The Ketiv (מנוות - Navot) suggests a physical habitation, a pasture or a temporary dwelling (naveh). The Keri (מניות - Nayot), however, connects the location to noy (beauty), specifically the spiritual beauty of Torah study and prophetic vision.

Through a lomdisch lens, this orthographic tension reflects the dual nature of David's sanctuary. Was Naioth merely a physical shelter (a naveh) where David hid from Saul's soldiers? Or was it a metaphysical powerhouse (a place of noy) where Samuel and David spent their nights mapping out the future site of the Beit HaMikdash?

The shift from the written vav to the spoken yod represents the transition from physical security to spiritual immunity. When David fled from Naioth, he was leaving a realm where physical force was suspended by prophetic beauty, returning to the harsh, geopolitical reality of Saul’s court. The Minchat Shai preserves this tension: even as David enters the world of political intrigue, his roots remain anchored in the Keri—the spiritual beauty of the Torah of Ramah.

4. Jacob vs. David: Midrash Lekach Tov on Filial Humility

The Midrash Lekach Tov on Genesis 31:37 contrasts Jacob’s confrontation with Laban with David’s confrontation with Saul:

"כי מששת את כל כלי מה מצאת מכל כלי ביתך. א"ר סימאי חתן שהוא דר אצל חמיו. אפשר לו שלא לקחת אפילו כלי אחד. ברם מה מצאת מכל כלי ביתך. אפי' מחט ואפילו צנורא. וענוותנותן של בנים. דכתיב ויברח דוד מניות ברמה (ש"א כ א). ומזכיר שפיכות דמים. שנא' כי מבקש את נפשי (שם). לו. ברם הכא כי דלקת (עלי) [אחרי]." "‘Although you have searched all my things, what have you found of all your household goods?’ R. Simai said: Is it possible for a son-in-law who lives with his father-in-law not to take even one vessel? Yet Jacob said, ‘What have you found... even a needle or a hook?’ And consider the humility of the children, as it is written, ‘And David fled from Naioth in Ramah’ I Samuel 20:1, and he mentions bloodshed, as it is said, ‘for he seeks my life’... but here [with Jacob], ‘that you have hotly pursued me’." [^7]

The Midrash draws a fascinating comparison between two sons-in-law who fled their fathers-in-law: Jacob fleeing Laban, and David fleeing Saul.

                       [The Son-in-Law's Flight]
                                   |
                  +----------------+----------------+
                  |                                 |
         [Jacob fleeing Laban]             [David fleeing Saul]
         - Civil/Monetary context          - Capital/Mortal context
         - "You hotly pursued me"          - "He seeks my life"
         - Confrontational defense         - Submissive, pleading defense

Analytical Breakdown

  • Jacob’s Context: Jacob’s dispute with Laban is primarily civil and monetary (mammon). Laban accuses Jacob of theft (the teraphim). Jacob, secure in his financial integrity, responds with aggressive self-righteousness: "What is my crime? What is my sin, that you have hotly pursued me?" Genesis 31:36. Jacob stands his ground, demanding a physical inspection of his goods.
  • David’s Context: David’s dispute with Saul is capital (nefashot). Saul does not accuse David of stealing a "needle or a hook"; he seeks his life (ki mevakesh et nafshi). Yet, despite the far greater severity of the threat, David’s language is remarkably humble and deferential. He does not confront Saul directly; instead, he appeals to Jonathan with brokenness, asking what he could have possibly done to deserve death.

The Midrash highlights "the humility of the children" (anvatnutan shel banim). In halakha, there is a fundamental distinction between a monetary dispute (dinei mamonot) and a capital dispute (dinei nefashot). In monetary matters, a person is permitted, and sometimes encouraged, to stand their ground and defend their property.

However, in capital matters, especially when dealing with a sovereign authority, the preservation of life (pikuach nefesh) supersedes all. David’s humility is not a sign of weakness, but a halakhic necessity. When one’s life is on the line, the ego must be totally nullified. David flees and speaks with extreme deference because he recognizes that survival takes precedence over pride.


Friction

The Core Kushya: Jonathan’s Cognitive Dissonance

How can Jonathan, with absolute certainty, assure David: "Heaven forbid! You shall not die. My father does not do anything, great or small, without disclosing it to me; why should my father conceal this matter from me? It cannot be!" I Samuel 20:2.

This statement is deeply problematic. In the preceding chapter, Saul had explicitly commanded Jonathan and all his servants to kill David I Samuel 19:1. Furthermore, Jonathan had already had to intercede on David’s behalf to appease Saul’s homicidal anger I Samuel 19:4-6.

Later in that same chapter, Saul attempts to spear David in his own house, and eventually sends assassins to surround David's home I Samuel 19:10-11.

How could Jonathan claim that Saul would not attempt to kill David without disclosing it to him? Is Jonathan suffering from a profound psychological denial, or is there a deeper, halakhic rationale behind his refusal to believe his father’s homicidal intent?

Terutz A: The Halakhic Status of Saul's "Ruach Ra'ah" (Temporal Insanity vs. Juridical Intent)

To resolve this friction, we must establish a halakhic distinction between two states of Saul’s personality: his manic-depressive state of "evil spirit" (ruach ra'ah) and his lucid state of royal judgment (da'at malchut).

In Chagigah 3b-4a, the Talmud defines the characteristics of a shoteh (an insane person), which include walking out alone at night, tearing one's clothes, and destroying what is given to him. Saul, under the influence of the ruach ra'ah, exhibits many of these classic symptoms: he strips off his clothes, lies naked on the ground, and hurls spears at his own family members I Samuel 18:10-11, I Samuel 19:24.

Jonathan was fully aware of these manic episodes. However, from a halakhic perspective, a shoteh lacks da'at (legal competence). Therefore, any action taken or declaration made by Saul during these episodes was legally void.

Jonathan reasoned that when Saul threw the spear or commanded his servants to kill David, he was acting under a state of temporary insanity (itim chalim itim shoteh—lucid at times, insane at times, as discussed in Rosh Hashanah 28a). Jonathan believed that these outbursts did not represent Saul's true, rational dynastic policy.

                         [Saul's Split Personality]
                                     |
                  +------------------+------------------+
                  |                                     |
       [State of "Ruach Ra'ah"]                [State of "Da'at Malchut"]
       - Temporary insanity                    - Rational, sovereign state
       - Lacks legal competence                - Legal, binding decisions
       - Outbursts are void                    - Disclosed to Jonathan
                  |                                     |
         (Jonathan's Assumption:               (David's Realization:
          Saul is not a "Rodef")               Saul's malice is permanent)

For Jonathan, a formal royal execution required a deliberate, juridical decree—a decision made in a state of da'at malchut. Because Saul had promised Jonathan under oath, "As the Lord lives, he shall not be put to death" I Samuel 19:6, Jonathan assumed that this rational, sworn commitment remained the baseline of his father's policy.

Jonathan believed that if Saul ever decided to formally revoke this oath and execute David through the legal machinery of the state, he would have to discuss it with his chief advisor and crown prince. Thus, Jonathan’s denial was not a psychological delusion, but a legal deduction: he refused to conflate the erratic outbursts of a temporarily incapacitated father with the formal, binding decrees of a sovereign king.

Terutz B: The Malbim's Division of "Great or Small" State Affairs

A second approach, developed from the Malbim, suggests that Jonathan's confidence lay in the definition of "anything, great or small" (davar gadol o davar katon).

Jonathan was the commander of the army and the heir apparent to the throne I Samuel 13:2, I Samuel 20:31. In any organized monarchy, the execution of a high-ranking military general and national hero like David is not a private matter; it is a major state action with massive geopolitical ramifications.

If Saul were to execute David, it would trigger a civil war, alienate the tribe of Judah, and destabilize the military front against the Philistines. Jonathan reasoned:

  1. "Great Matter" (Davar Gadol): A formal state execution of a national hero. This would require mobilization of troops and political alignment, which Saul could not hide from his top general (Jonathan).
  2. "Small Matter" (Davar Katon): Minor administrative or courtly decisions. Even these, Saul routinely shared with his son.

Therefore, Jonathan concluded that it was politically impossible for Saul to execute David in secret. He did not deny that Saul wanted David dead; rather, he argued that Saul could not execute this desire without utilizing the state apparatus, which Jonathan controlled.

What Jonathan failed to realize—and what David had to prove to him through the sign of the arrows—was that Saul’s hatred had bypassed all rational statecraft. Saul was willing to destroy his own dynasty, alienate his son, and destabilize his kingdom just to eliminate his perceived rival. David’s genius lay in forcing Jonathan to see that Saul’s obsession was no longer a "state matter" governed by rational politics, but a consuming, extrajudicial madness that would bypass all institutional checks and balances.


Intertext

1. The Jacob-Laban Connection: Linguistic and Conceptual Echoes

The verbal parallels between David’s plea in I Samuel 20:1 and Jacob’s confrontation with Laban in Genesis 31:36-37 are striking and merit a closer textual reading.

====================================================================================
GENESIS 31:36                                  I SAMUEL 20:1
====================================================================================
"מַה־פִּשְׁעִי מֶה חַטָּאתִי                      "מֶה עָשִׂיתִי מֶה־עֲוֺנִי וּמֶה־חַטָּאתִי
כִּי דָלַקְתָּ אַחֲרָֽי׃"                         לִפְנֵי אָבִיךָ כִּי מְבַקֵּשׁ אֶת־נַפְשִֽׁי׃"
------------------------------------------------------------------------------------
"What is my crime? What is my sin,             "What have I done? What is my iniquity?
that you have hotly pursued me?"               And what is my sin before your father..."
====================================================================================

Textual Analysis

Jacob uses the terms פֶּשַׁע (pesha - willful rebellion) and חַטָּאָה (chata'ah - missing the mark/unintentional offense). He is responding to a charge of theft. Jacob’s tone is defiant because he knows that in a civil court (dinei mamonot), the burden of proof lies on the claimant (hamotzi mechavero alav harayah - Bava Kamma 46a).

David, however, adds a third term: עָוֺן (avon - deliberate iniquity). Furthermore, instead of accusing Saul of "hotly pursuing" him (dalakta acharay), David states the stark reality: "he seeks my life" (mevakesh et nafshi).

This linguistic escalation marks the transition from a civil framework to a theocratic-capital framework. While Jacob is defending his financial integrity, David is defending his physical existence.

Yet, David’s inclusion of "before your father" (lifnei avicha) shifts the focus of the guilt. David is not merely asking what he did wrong; he is asking what he did to Saul. He frames his entire existence as being in service to Saul's monarchy.

This parallel underscores the tragic irony of the Davidic narrative: like Jacob, who served Laban faithfully for twenty years only to be treated as a thief, David served Saul with absolute loyalty, only to be hunted like a rebel.

2. The Halakhic Conflict: Covenantal Oaths vs. Filial Piety (Kibbud Av)

A major halakhic tension running through this chapter is the conflict between Jonathan’s oath of covenant to David I Samuel 20:16-17 and his biblical obligation to honor his father, Saul Exodus 20:12.

By aiding David’s escape, Jonathan is actively undermining his father’s royal authority and directly disobeying his explicit commands. He even lies to his father regarding David's whereabouts, claiming David went to Bethlehem for a family sacrifice I Samuel 20:28-29.

How does Halakha resolve a direct conflict between Kibbud Av (honoring parents) and a Shevuah (an oath) or the preservation of life (Pikuach Nefesh)?

The Talmud in Yevamot 6a derives a fundamental limitation on parental authority:

"יכול שאמר לו אביו: היטמא, או שאמר לו: אל תחזיר... תלמוד לומר: 'איש אמו ואביו תיראו ואת שבתותי תשמורו' - כולכם חייבין בכבודי." "Could it be that if one's father said to him: 'Defile yourself [if the father is a priest],' or 'Do not return [a lost object],' that he must obey him? The verse states: 'You shall each revere his mother and father, and keep My sabbaths' Leviticus 19:3—all of you are obligated in My honor." [^8]

From this, the Halakha rules that if a parent commands a child to violate any Torah prohibition—whether a negative or positive commandment—the child must refuse Shulchan Aruch, Yoreh Deah 240:15.

In our case, Saul’s command to deliver David for execution was a command to participate in murder (shfikhut damim). Murder is one of the three cardinal sins for which one must "be killed rather than transgress" (yehareg ve-al ya'avor - Sanhedrin 74a).

Therefore, Jonathan was halakhically forbidden to obey his father’s command to surrender David. His obligation to the divine law, which forbids the shedding of innocent blood, completely overrode his obligation to honor his father.

                      [Conflict of Halakhic Duties]
                                    |
                  +-----------------+-----------------+
                  |                                   |
         [Kibbud Av (Exodus 20)]            [Command to Murder (Violates Law)]
         - Honor and obey parent            - Saul orders David's death
         - Subject to Divine Law            - Absolute veto: "All must honor God"
                  |                                   |
                  +-----------------+-----------------+
                                    |
                        [Jonathan Must Disobey Saul]

Furthermore, Jonathan’s oath to David was an oath to perform a mitzvah—the saving of a life (hatzalat nefashot). While an oath cannot normally override a Torah commandment (ein nishba'in levatel eth ha-mitzvah - Nedarim 8a), in this case, the oath was aligned with the Torah's mandate to save those in danger Leviticus 19:16.

Thus, Jonathan's deception of his father was not a moral compromise, but a halakhically mandated course of action: when a parent’s royal command conflicts with the preservation of innocent life, the child must choose life.


Psak/Practice

How does this dramatic biblical narrative translate into halakhic practice and meta-psak heuristics?

1. Safek Pikuach Nefesh (Doubt of Mortal Danger)

One of the most far-reaching halakhic principles derived from David’s conduct is the assessment of mortal danger. When Jonathan assures David that there is no danger, David responds:

"כְּפֶשַׂע בֵּינִי וּבֵין הַמָּוֶת" "There is only a step between me and death." — I Samuel 20:3

From a halakhic perspective, who is authorized to assess whether a situation constitutes a life-threatening emergency?

  • Jonathan’s View: An outside observer, even a highly placed expert with access to intelligence, may assess the situation as safe.
  • David’s View: The individual who is directly targeted or experiencing the threat has a heightened, intuitive understanding of the danger.

The Halakha rules in accordance with David. In the laws of Yom Kippur, the Shulchan Aruch rules:

"חולה שאמר צריך אני לאכול, אפילו אם הרופאים אומרים אינו צריך, שומעין לחולה." "A sick person who says 'I need to eat' [on Yom Kippur]—even if the doctors say he does not need to, we listen to the sick person." — Shulchan Aruch, Orach Chayim 618:1 [^9]

This is based on the verse in Proverbs 14:10: "The heart knows its own bitterness" (lev yodea marat nafsho).

In matters of Pikuach Nefesh, we do not adopt a "wait and see" approach, nor do we defer entirely to optimistic external evaluations. If an individual feels their life is in danger—if they perceive that "there is only a step between me and death"—we violate all prohibitions (such as desecrating Shabbat or eating on Yom Kippur) to save them, even if experts deem the threat highly improbable.

2. The Permission to Deceive to Save a Life

Jonathan’s fabrication of David’s journey to Bethlehem I Samuel 20:6 provides a direct scriptural precedent for the halakhic permission to lie or mislead to protect someone from an unjust pursuer (rodef).

The Shulchan Aruch codifies this in the laws of vows:

"נודרים להרגין ולחרמין ולמוכסין שהיא תרומה... אע"פ שאינה תרומה." "One may vow to murderers, robbers, or tax collectors [who are acting illegally] that a certain item is consecrated (terumah)... even though it is not." — Shulchan Aruch, Yoreh Deah 232:14 [^10]

When dealing with an illegal extortionist or a homicidal threat, the obligation of truthfulness is suspended. Language is no longer a tool for objective representation, but a defensive shield to preserve human life. Jonathan’s lie to Saul was not a blemish on his integrity, but a masterful application of this halakhic principle: when language is weaponized by a rodef, the defender is fully authorized to use deceptive speech to neutralize the threat.


Takeaway

True covenantal loyalty (b'rit) requires us to recognize when systemic authority has devolved into lawless pursuit, mandating that we prioritize the preservation of life over parental honor, political survival, and even absolute truth.


Footnotes

[^1]: Radak on I Samuel 20:1, s.v. "ויברח דוד". [^2]: Metzudat David on I Samuel 20:1, s.v. "ויברח". [^3]: Malbim on I Samuel 20:1, s.v. "ויברח". [^4]: Malbim on I Samuel 20:1, s.v. "מה עשיתי". [^5]: Minchat Shai on I Samuel 20:1, s.v. "מנוות". [^6]: Eruvin 18b, see also Rashi ad loc. [^7]: Midrash Lekach Tov, Genesis 31:37. [^8]: Yevamot 6a; see also Sifra on Leviticus 19:3. [^9]: Shulchan Aruch, Orach Chayim 618:1; derived from Yoma 83a. [^10]: Shulchan Aruch, Yoreh Deah 232:14; derived from Nedarim 27b.