וַיָּ֤שֶׂם הָעֶ֙בֶד֙ אֶת־יָד֔וֹ תַּ֛חַת יֶ֥רֶךְ אַבְרָהָ֖ם אֲדֹנָ֑יו וַיִּשָּׁ֣בַֽע ל֔וֹ עַל־הַדָּבָ֖ר הַזֶּֽה׃
Lalu hamba itu meletakkan tangannya di bawah pangkal paha Abraham, tuannya, dan bersumpah kepadanya mengenai perkara ini.
Ramban
YIDOR NEDER LA’SHEM (VOWETH A VOW ‘UNTO’ THE ETERNAL). The meaning of [the expression] ‘yidor neder la’shem’ is not like that of ‘asher nishba la’shem (how he — David — swore ‘unto’ the Eternal),31Ibid., 132:2. for that [expression mentioned by David] is like ‘vayishava lo’ (and he swore ‘to him’)32This is in reference either to Genesis 24:9, where Eliezer swore to Abraham to find a wife for Isaac from the country of his birthplace, or to Genesis 47:31, Joseph swearing to Jacob that he would bury him together with his fathers. In both cases the meaning of the prepositional lamed [‘lo’] is its literal meaning — “unto him,” and the intention is to say that the oath was “for his benefit.” Likewise the prepositional lamed [in the word la’shem] used by David has its literal meaning — “for ‘the benefit’ [so to say] and glory of G-d,” since the oath concerned his determination to build the House of G-d. which means that he swore to him for his [the recipient’s] benefit. But [the use of the prepositional lamed in the case of vows is equivalent to the use of the preposition beth (“by”)33The gist of Ramban’s reasoning is as follows: The prepositional lamed in the case of oaths [in the examples cited above] has the meaning of “to” — to the benefit of the recipient, as is the case of Eliezer where the oath was for the benefit of Abraham. This principle, however, cannot be made to apply to vows, since in our verse it says if a man vows a vow ‘la’shem,’ and the verse is not speaking exclusively about vows to the benefit of the Sanctuary but refers to vows of all sorts, even of secular matters. Hence we must say that the prepositional lamed in vows has the same meaning as the beth [not the lamed] in oaths, which in both cases means “by” — by G-d. In other words, the prepositional lamed in vows and the beth in oaths are identical in meaning. Finally, Ramban will conclude that the Cabala does offer an explanation why a different preposition is used in each case. Thus it is shown that the mystic character of the Sacred Language is deeply embedded in the text of the Torah. in the case of oaths, for] in the case of oaths Scripture says: ‘u’vishmo’ (and ‘by’ His Name) shalt thou swear;34Deuteronomy 6:13. v’ashbiacha ‘ba’shem’ (and I will make thee swear ‘by’ the Eternal);35Genesis 24:3. as I swore ‘lecha’ (unto thee) ‘ba’shem’ (‘by’ the Eternal), the G-d of Israel, saying: Assuredly Solomon thy son shall reign after me;36I Kings 1:30. swear ‘li’ (unto me) here ‘bei’Elokim’ (‘by’ G-d).37Genesis 21:23. But in the case of a vow Scripture does not say: “he vows ‘ba’shem’ (‘by’ G-d)” but la’shem (‘to’ G-d). The Sages in the Sifre have already alluded to the reason for this matter [the different terminology], saying:38Sifre, Matoth 153. See Vol. I, p. 66, where Ramban quotes this Sifre. “What is the difference between vows and oaths? Vows are like vowing39This is the text in the Sifre and in Ramban here. In Genesis, however, Ramban has “swearing” (Vol. I, p. 66). The intent of the texts in both places is equivalent. ‘by the life of the King;’ oaths are like swearing ‘by the King Himself.’ Although there is no [clear] proof for this explanation [in Scripture], there is an allusion to it: By the living G-d, and by the life of your soul. I will not leave thee.”40II Kings 4:30. See Vol. I, p. 66, Note 290 where this text is explained in detail. And the secret thereof is that the shevuah (oath) is derived from the word shivah [“seven” — alluding to the seven Emanations], for she [wisdom] hath builded her house, she hath hewn out her seven pillars,41Proverbs 9:1. whereas the vow is on [the level of] understanding, the beginning of His way, the first of His works of old.42Ibid., 8:22. Thus you find that vows take precedence over the Torah, and therefore they apply to commandments just as to optional matters [as explained above]. Thus all vows are la’shem (“to” the Eternal), whereas all who swear [do so] “by” Him.
Rashi
When the Lord shall have washed away Heb. אִם [usually “if.”] When the Lord shall have washed away. There are instances of אִם being used in this manner in the usage of כִּי ; and so (Job 8:18): “But when (אִם) men destroy him from his place,” is [equivalent to] כִּי יְבַלְּעֶנּוּ. Also (Gen. 24:9): “Until when (אִם) they will have finished drinking.”
Or HaChaim
ויאמר אנכי אעשה כדבריך. He said: "l will do in accordance with your instructions." Why did Joseph have to announce that he was going to do all this? All he had to do was to place his hand where his father had asked and make the promise and that would be his reply to his father's request. This is what Eliezer did when Abraham made him swear an oath concerning his selecting a wife for Isaac (Genesis 24,9).