Musar su Genesi 25:28

ויאהב יצחק את עשו כי ציד בפיו ורבקה אוהבת את יעקב. We have an allusion here to the well-known statement in Avot 5,19 that any love which is based on something material will not endure once the object upon which it is based disappears, whereas love which is not based on something transient will endure. Isaac's love for Esau was founded on the material things Esau provided, and therefore it could not endure. This may well be the reason the Torah describes Isaac's love for Esau in the past tense, i.e. ויאהב, whereas Rebeccah's love for Jacob is described in the present tense, i.e. אוהבת, an ongoing love.

Jacob was the descendant of Isaac and Rebeccah. In the case of Abraham's son Isaac, G–d had promised Abraham only כי ביצחק יקרא לך זרע, that part of Isaac would be his worthy seed, not all of Isaac. The Torah reports that Rebeccah loved Jacob (25,28). We have said that then the world was filled with Jacob's "beauty," which was of the kind once possessed by Adam, מטתו שלמה, Jacob's bed was perfect, i.e. all his children were loyal to his teachings which enabled him to become known as ישראל. Since only ישראל is called אדם, the connection between Jacob and Adam is clear.

The second introduction needed to understand the whole issue is the fact that Esau and Jacob were twins inside Rebeccah's womb, and that she was the mother of both of them. This means that she was like the crucible within which Jacob was refined, whereas Esau at the same time absorbed all the residual polluted material of the original serpent that had still cleaved to Rebeccah in her capacity as Laban's sister. Esau inherited all the falseness of Laban. This left Jacob like pure, refined silver. That is what our sages had in mind when they referred to Jacob's beauty as equaling that of Adam (before his sin). The fact that Esau had absorbed all the negative residual elements within Rebeccah had enabled Jacob to become the pious person he was. Rebeccah loved Jacob; Isaac loved Esau more. The deeper reason for this is, as we have already explained, that there was some affinity between Isaac, whose root was the emanation of דין, the same emanation as the one the serpent=Satan=Esau was rooted in. Rebeccah, on the other hand, loved Jacob, seeing that her appearance was just like that of her mother-in-law Sarah, as we have explained. When Sarah is described in Genesis 20,3 as בעולת בעל, the Talmud Ketuvot 61 describes this as meaning that her husband was in a state of ascension at the time. The Torah compliments Sarah by testifying that together with her husband she ascended to higher spiritual regions. Rebeccah experienced something similar. We know that Isaac was described as עולה תמימה, an unblemished total offering [ עולה in the sense of something that ascends Ed.], at the time he was bound on the altar at Moriah. Our Rabbis say that nonetheless Isaac was like a קרבן עולה ויורד, in the matter of the עקדה, meaning that at different times he was at different spiritual levels. While he was bound on the altar, for instance, he was on a higher spiritual level than when he descended from the altar, aware that he was not to be sacrificed after all, seeing that G–d had appointed an alternative offering in his stead, namely the ram that was caught in the thicket by its horns (Genesis 22,13). Jacob was called an איש תם, the word תם referring to his spiritual ascension. Esau, on the other hand, though from a holy source as we explained when we described his head as being cradled by Isaac , was of the caliber that was liable to descend rather than to ascend spiritually.