Or HaChaim on Genesis 26:28/אור החיים על בראשית כ״ו:כ״ח

1 ויאמרו ראו ראינו וג׳. "We have seen very clearly, etc." Why did Avimelech and company repeat: "we have seen, seen?" There are also other nuances in their remarks which we need to analyse.

2Basically, Avimelech and company responded to Isaac's questions by saying that they really intended to respond to all Isaac had said. As to the covenant concluded between Abraham and Avimelech they said: "we have seen,seen." They claimed that there were two reasons why they could not rely on Abraham's vow. One was, as we stated, that Abraham's vow was made in private, the other that Abraham had not been a beneficiary of Avimelech and thus was at liberty to annul his vow even without Avimelech's presence or consent. Furthermore, they said that they did realise that only when they renewed said covenant with Isaac would he consider his father's vow as binding and ironclad. Avimelech added that when he concluded his covenant with Abraham he had not been careful to do it in such a way that it would remain irrevocable.

3Should Isaac be angered that Avimelech had not bothered to secure similar guarantees from his brother Ishmael who was, after all, Abraham's elder son, they explained this by saying they had observed that it ws Isaac who was both personally powerful and obviously enjoyed G'd's blessing and support. Although Isaac had pointed out that the fact they had expelled him was a sign of their hatred for him, they had convinced themselves that if he was worthy of G'd's blessing there was no cause to hate him.

4Concerning Isaac's complaint that they had not been honest with him and that it was an effrontery therefore to ask him for favours, ראו ראינו, they felt intellectually that the permanent validity of the covenant with Abraham would be guaranteed only if they renewed it at this time. I shall forthwith explain how we can read all this out of their carefully chosen words.

5ונאמר תהי נא אלה בינינו, we said: "let there be an oath between us, etc." The word ונאמר is past tense. They now began to explain the reason they had expelled Isaac from Gerar; as long as Isaac remained with them in Gerar it was legally impossible for the oath they had in mind to become irrevocable. We learn in Nedarim 27 that it is permissible to revoke certain vows without the need to appear before a tribunal. Examples are vows which were made under pressure from people who are reputed to commit murder in order to enrich themselves, or when facing robbers intent merely on confiscating one's property, or when facing tax collectors who exceed their authority. The school of Hillel taught that even when such vows were phrased as an oath, no legal mechanism is required to revoke them (when the danger is over). Concerning the above Mishnah, Maha'rik writes in Yore De-ah 232, that "anyone who swears an oath or makes a vow under duresss, such oath or vow is not legally binding." It suffices to annul such vows or oaths in one's heart; Joseph, however, did not annul his vow concerning his promise to Pharaoh not to reveal that the latter did not understand the Hebrew language, nor did Zedekiah annul his promise to Nebuchadnezzar in his heart. This ruling is valid even if the person who made the vow had been compensated in some form for the vow he was about to make. Avimelech and his company were afraid that Isaac might invoke this ruling to free himself of any vow if such an undertaking were to be made while he was in Avimelech's territory, i.e. under his rule, and therefore under some kind of duress. Therefore they came to a place over which Avimelech had no authority so that any undertaking by Isaac would be completely voluntary and therefore binding upon him. This is also clear from the writings of Nachmanides on the subject. The words תהי נא were meant to emphasise that the covenant to be undertaken now was to be different from the one previous in that it would remain valid, i.e. תהי. When they claimed at the time they expelled Isaac that he had become too powerful, this had only been a pretext to make him leave; their true reason had been to create a situation in which Isaac's oath would be binding upon him. They may also have used that pretext so that Isaac could not try to dissuade them by telling them that their fears that he would not honour his commitment were unfounded. There were some other considerations which I will come back to later.

6בינותינו בינינו ובינך, "between us, i.e. between us and you." The reason they added the apparently unnecessary word בינותינו was to reinforce the existing agreement concluded with Abraham, and to add a new covenant with Isaac. They wanted to examine whether Isaac considered the agreement with Abraham as valid for him. Perhaps Avimelech was afraid that G'd would renew His promise to give the land of Palestine to Isaac and the latter would give part of his inheritance to Esau. Avimelech did not consider Esau as the seed of Abraham seeing that G'd had specificaly said to Abraham that כי ביצחק יקרא לך זרע, that only part of Isaac's seed would be considered Abraham's seed (21,12). Should Isaac then decide to give the land of the Philistines to Esau, he, Avimelech, would not have a legal leg to stand on in a dispute with Isaac, seeing that the covenant with Abraham which covered Abraham's descendants down to his great-grandchildren would not have been breached thereby. Esau would argue that his inheritance was due to a promise made by G'd to his father Isaac, not through a promise made by G'd to Abraham who had delayed it from becoming effective for four generations. These were the considerations which prompted Avimelech to make Isaac swear a separate oath. According to Rashi the word בינותינו alluded to the validity of the agreement for several generations.

7This word may also allude to the fact that Avimelech wanted the undertaking to be a public one. The repetition of the word בינינו was meant to emphasise the mutual agreement that prevailed at the time of the new covenant and which would make any future attempt to revoke it subject to mutual agreement.