Gen 24:8

“'ונקית משבעתי וגו THEN SHALT THOU BE CLEAR FROM THIS MY OATH etc. — and take a wife for him from the daughters of Aner or Eshcol or Mamre. רק את בני וגו ONLY [BRING NOT] MY SON [THITHER] etc. — The word רק narrows and limits (מעוט) the sense: it is only my son who may not go back there, but Jacob, my son’s son, in the end will go back there to find a wife (Genesis Rabbah 59:10).”

“THEN THOU SHALT BE CLEAR FROM THIS MY OATH. Abraham did not permit him to take a wife for Isaac from the daughters of Canaan, but he would be free [from the oath if Isaac were to do it on his own] and the Eternal do that which is good in His sight. But Rashi wrote, “And take a wife for him from the daughters of Aner, Eshkol or Mamre.” Now if they were Canaanites, far be it from him! And in truth they were of the seed of Canaan for Scripture says, Mamre the Amorite, brother of Eshkol, and brother of Aner. And in Bereshith Rabbah, the Rabbis have said: “That thou shalt not take a wife, etc. He warned him against the daughters of Canaan, Aner, Eshkol, and Mamre.” For it was with reference to Aner, Eshkol, and Mamre that Abraham said, Among whom I dwell, since he did not dwell among all the Canaanites as they were many nations. But he warned him against these his confederates, and all the more against the others. But the verse, Then thou shalt be clear from this my oath, means that the servant would be free from the oath if Isaac would want to do it on his own, and Abraham relied on his knowledge that his righteous son Isaac would listen to his father and that he would beware of them and go instead to Ishmael or to Lot and the other nations. It is possible that from this my oath is a hint to that which he said, And thou shalt take a wife unto my son from there, since perhaps the oath was for everything, [meaning that the oath covered two points: a) that he should not take for him a wife from the daughters of Canaan, and b) that he should go to his family. In case they refused, he would be free from the second oath, while the first oath would always remain in effect]. Accordingly, then thou shalt be clear from this my oath does not allude to that which Abraham told him, Thou shalt not take a wife unto my son of the daughters of the Canaanites, [since he never freed him from this oath]. This explains the word zoth (this) — [thou shalt be clear from ‘this’ my oath — implying there was another oath from which he was not freed]. Therefore, the servant said, That I may turn to the right hand, or to the left, and he did not say, “I would return [to the land of Canaan,” since he was not freed from the oath not to take a wife from the daughters of Canaan].”