The Pasuk states, “VaYe’ehav Yitzchak Et Eisav Ki Tzayid BeFiv VeRivkah Ohevet Et Ya’akov,” “Yitzchak loved Eisav for trapping was in his mouth, but Rivkah loved Ya’akov” (BeReishit 25:2). Two obvious questions come to mind when reading these Pesukim. Firstly, is it possible that Yitzchak loves Eisav more than Ya’akov? Isn’t Ya’akov the ideal child, a Yerei Shamayim like his father? Conversely, if Yitzchak truly loves Eisav more, indicating that he is special in some way, why doesn’t Rivkah love him too? To make the first question more difficult, a few Pesukim earlier Hashem tells Rivkah, “VeRav Ya’avod Tza’ir,” “And the older (Eisav) shall serve the younger (Ya’akov)” (25:23). Why doesn’t Yitzchak realize that Ya’akov is to be the chosen son, favored by Hashem?
To answer these questions, we’ll first look at Radak and Ibn Ezra. They point out the most obvious explanation to this Pasuk, which is that Yitzchak loved Eisav because he brought him delicious meats. Based on this interpretation, the Or HaChayim answers the second question – Rivkah came from a house where it was normal to eat tasty meats, so she was not persuaded to love Eisav because of them. The problem with the answers of Radak and Ibn Ezra is that Yitzchak seems to love Eisav for such a shallow reason.
Rashi cites Midrash Tanchuma that states that the trapping that Eisav did was with his mouth, meaning he would trick Yitzchak into thinking he was a very pious individual by asking him questions on matters he pretended he had learned that day. According to this answer, though, Yitzchak should have loved Ya’akov equally, because the Torah states that Ya’akov was a Yosheiv Ohalim, one who dwells in tents, and (according to Rashi’s explanation) studied much more Torah than did Eisav.
Ramban presents a very profound explanation that seems to answer all of our questions. He says that “Ki Tzayid BeFiv” can be understood as saying that Eisav is “trapping in [Yitzchak’s] mouth.” In other words, Eisav is the type of son that is constantly getting his father food, since he is always thinking about his father and displaying Kibud Av, respect for one’s father. Yitzchak thinks that because of Eisav’s Kibud Av he must also have a great amount of respect for Hashem, that being the true reason Yitzchak loves Eisav more than Ya’akov. The Or HaChayim supports this explanation by showing why this would cause Rivkah to disagree with Yitzchak and love Ya’akov more. He explains that later on in the Parashah (27:45), Eisav says that he wants to kill Ya’akov but he doesn’t want to cause his father pain. The fact that Eisav did not mention his mother seems to indicate that Eisav respects only his father, and in fact, even that respect is not sincere. Eisav shows respect for his father only because he wants his father to bless him, which his mother could not do. Clearly, his Kibud Av isn’t genuine, and he doesn’t show any form of Kavod to his mother. Rivkah notices this, and that is the reason she doesn’t love Eisav the way Yitzchak does.
The reason Yitzchak loved Eisav was because it made sense from his point of view. Eisav seemed like a respectful child to Yitzchak and since the whole basis of Kibud Av is respect for Hashem, he believed that Eisav must be God-fearing and therefore worthy of his love.