Kommentar zu Bereschit 21:23

ולניני ולנכדי NOR WITH MY SON NOR WITH MY SON’S SON — thus far extends a man’s pity for his descendants (Genesis Rabbah 54:2).

NOW THEREFORE SWEAR UNTO ME HERE BY G-D ‘IM’ (IF) YOU WILL BE FALSE TO ME. The word im always expresses doubt — do not think of it in any other way³⁴⁵Ramban’s intent is to differ with Rashi, who, in Leviticus 2:14, explains im to mean “that.” See Ramban there, where he explains it in a manner consistent with his teaching here. — and it appears in most places in connection with an oath: If you will be false to me;³⁴⁶In the present verse. And therefore I have sworn unto the house of Eli ‘im’ (if) the iniquity of Eli’s house shall be expiated;³⁴⁷I Samuel 3:14. Once I have sworn by My holiness ‘im’ (if) I will be false unto David;³⁴⁸Psalms 89:36. ‘im’ (if) they should enter into My rest;³⁴⁹Ibid., 95:11. And he was wroth, and swore, saying, ‘im’ (if) one of these men will see.³⁵⁰Deuteronomy 1:34-35.
The purport of this is that since oaths are given with imprecation, Abimelech is stating, “Swear to me, saying, G-d do so to me, and more also³⁵¹II Samuel 3:35. if you will be false to me.” Likewise it is said, Let there now be an oath between us.³⁵²Further, 26:28. And in the matter of a Divine oath: I have sworn by My holiness if I will be false to David;³⁴⁸Psalms 89:36. if the iniquity of Eli’s house shall be expiated,³⁴⁷I Samuel 3:14. meaning “If that will be so, then My word is not true,” and in similar cases, since it does not want to expressly state the condition.³⁵³Namely, that “if that be so, My word is not true.” Scripture modifies and shortens these expressions. A similar case of a shortened condition is the verse, And Jabez called on the G-d of Israel, saying: Oh that Thou wouldest bless me indeed, and enlarge my border, etc., and that Thou wouldest work deliverance from evil that it may not pain me. And G-d granted him that which he requested.³⁵⁴I Chronicles 4:10. Here the entire condition³⁵⁵Namely, his vow of offering to G-d. is missing. A similar example is the verse, If they will see the land,³⁵⁶Numbers 14:23. referring back to the first verse, As I live, and all shall be filled with the glory of the Eternal,³⁵⁷Ibid., Verse 21. and Scripture shortens the Divine oath.
The expression, false to me, is because Abimelech was a king, and Abraham dwelt in his land. [Thus, if Abraham were to do him evil, it would be an act of disloyalty towards him in his royal capacity], or it would be a betrayal of Abimelech’s love for him, as he [Abimelech] was his trustworthy friend, honoring him and doing his will. For you see that Abraham found no fault with him except the well of water, which Abimelech’s servants had violently taken away,³⁵⁸Verse 25 here. and the king said to him, According to the kindness that I have done unto thee.³⁵⁹Verse 23 here.

ולנכדי, to my grandson.