Midrasch zu Wajikra 1:16

(Numb. 30:2–3 [1–2]:) THEN MOSES SPOKE UNTO THE HEADS OF THE TRIBES …: WHEN SOMEONE MAKES A VOW (neder) TO THE LORD, <….> Let our master instruct us: What about konamot (i.e., vows of abstinence) and vows (nedarim)?¹Tanh., Numb. 9:1. Thus have our masters taught (in Ned. 2:1): <IF ONE MAKES> A KONAM (i.e., a vow of absitinence) [THAT HE WILL NOT SLEEP, THAT HE WILL NOT SPEAK, THAT HE WILL NOT WALK; IF HE UTTERS A KONAM TO HIS WIFE THAT HE WILL NOT HAVE MARITAL RELATIONS WITH HER, SUCH A ONE IS LIABLE TO <THE INJUNCTION> (in Numb. 30:3 [2]): HE SHALL NOT BREAK HIS WORD. <IF HE SWEARS> AN OATH (shevu'ah)] THAT HE WILL NOT SLEEP, THAT HE WILL NOT SPEAK, THAT HE WILL NOT WALK, HE IS FORBIDDEN <TO DO SO>.²Cf. Ned. 2:2-5; Ned. 13b, 14b-15a; 20a; yNed. 2:2-5 (37b-6); above, Lev. 1:16; cf. Matthew 5:33-37; 23:16-22; James 5:12. Oaths (shevu'ot) carry more weight than vows (nedarim); and vows, than oaths. How so? <If one makes> a konam not to make a Sukkah, not to take up a Lulab, not to put on phylacteries, in the case of vows (nedarim) it is forbidden to put them on or to make them, even though they are commanded (in Torah); but in the case of oaths (shevu'ot) it is permitted, because one does not swear to transgress against the commandments. The Holy One said to the Israelites: Be circumspect with your vows (nedarim) and do not break them, for all who break vows (nedarim) end up in being faithless in oaths (shevu'ot). Moreover, the one who is faithless in oaths is denying me and will never have forgiveness, as stated (in Exod. 20:7 = Deut. 5:11): <YOU SHALL NOT TAKE THE NAME OF THE LORD YOUR GOD IN VAIN,> FOR THE LORD WILL NOT EXONERATE <ONE WHO TAKES HIS NAME IN VAIN>. It is also written (in Jer. 4:2): AND YOU SHALL SWEAR: AS THE LORD LIVES, <IN TRUTH, IN JUSTICE, AND IN RIGHTOUSNESS>. The Holy One said to the Israelites: Do not think that you have permission to swear in my name even in truth.³Numb. R. 22:1. You are not entitled to swear by my name unless you possess all the following attributes (of Deut. 10:20): THE LORD YOUR GOD YOU SHALL FEAR, [HIM YOU SHALL SERVE, TO HIM YOU SHALL HOLD FAST, AND BY HIM YOU SHALL SWEAR]:

(Numb. 30:3:) “When someone makes a vow (neder) to the Lord.” Let our master instruct us: How are konamot (i.e., vows of abstinence) and vows (nedarim)? Thus have our masters taught (in Ned. 2:1): [If one makes] a konam (i.e., a vow of absitinence) [that he will not sleep, that he will not speak; [if he utters a konam to his wife] “that I will not have marital relations with you,” such a one is liable to [the injunction] (in Numb. 30:3), “he shall not break his word.” [If he swears] an oath (shevu'ah)] that he will not sleep, that he will not walk, he is forbidden [to do so].¹Cf. Ned. 2:2-5; Ned. 13b, 14b-15a; 20a; yNed. 2:2-5 (37b-6); above, Lev. 1:16. Oaths (shevu'ot) carry more weight than vows (nedarim); and vows, than oaths. How so? [if one makes] a konam not to make a sukkah, not to take up a lulab, not to put on phylacteries, in the case of vows (nedarim) it is forbidden to put them on or to make them, even though they are commandments (of the Torah); but in the case of oaths (shevu'ot) it is permitted, because one does not swear to transgress against the commandments. The Holy One, blessed be He, said to Israel, “Be circumspect with your vows (nedarim) and do not break them; for all who break vows (nedarim) end up in being faithless in oaths (shevu'ot).” And the one who is faithless in oaths is denying the Holy One, blessed be He through it and will never have forgiveness, as stated (in Exod. 20:7 = Deut. 5:11), “for the Lord will not exonerate [one who takes His name in vain].” [Yet] it is also written (in Jer. 4:2), “And you shall swear, ‘As the Lord lives,’ [in truth, in justice, and in righteousness].” The Holy One, blessed be He, said to Israel, “Do not think that you have permission to swear in My name even in truth.²Numb. R. 22:1. You are not entitled to swear by My name unless you possess all the following attributes (of Deut. 10:20), “The Lord your God you shall fear, Him you shall serve, to Him you shall hold fast, [and by Him you shall swear]”: That you should be like those three who were called God-fearing, Abraham, Job, and Joseph: Abraham of whom it is written (in Gen. 22:12), “For now I know that you fear [God].” Concerning Job it is written (in Job 1:1), “the man was blameless [and upright, one who feared God].” Concerning Joseph it is written (in Gen. 42:18), “for I fear God.” Ergo (in Deut. 10:20), “The Lord your God you shall fear.” (Deut. 10:20, cont.:) “Him you shall serve.” [You do so,] if you turn [all] your attention to the Torah, fulfill [its] commandments and have no other work (abodah). It therefore is stated (ibid.), “Him you shall serve (rt.: 'bd).” (Deut. 10:20, cont.:) “To Him you shall hold fast.” Can one hold fast to the Divine Presence? Moreover, has it not already been stated (in Deut. 4:24), “For the Lord your God is a consuming fire?” It is simply [being stated with reference to] anyone marrying off his daughter to a scholar who reads [Scripture] and recites [Mishnah], that he engage in commerce³Gk.: pragmateia. for him and have him benefit from his assets.⁴Ket. 111b; cf. Sot. 14a. It is with reference to [such a] one that it is stated (in Deut. 10:20), “to him you shall hold fast.”
If you have all these [attributes] you may swear; if not, you are not entitled to swear. There is a story about King [Jannai], that he had two thousand towns and they all were destroyed because of a true oath. (Numbers 30:17:) “Between a man and his wife, between a father and his daughter.” Just like a man only annuls vows of self-affliction and matters between him and her, so too a father only annuls with regards to self-affliction and what is between him and her.

1) (Vayikra 1:16): "And he shall cast it" (the crop, etc.): "it" — that of a kasher offering, and not that of a pasul offering; "it" — not (that of) a bird sin-offering, (whose crop the Cohein may eat if he so wishes). "it" is cast (in the place of the ashes), and not the (corresponding parts of the) burnt-offering of a beast, (which are rinsed and sacrificed).