Every small child knows this story: two brothers – one righteous and the other wicked. Yaakov the righteous one cooked a lentil stew, and Eisav the wicked one came and asked (25:30), ‘הלעיטני נא מן האדום האדום הזה’ - “Pour into me now some of this red, red one.” And what happened in the end? Yaakov received the birthright, and Eisav received a new name: ‘על כן קרא שמו אדום’ - “Therefore he called his name Edom.” And we want to understand: who called him “Edom”? And why? After all, they gave him a name when he was born: “Eisav.” For this we must try to return to the house of Yitzchak and attempt to understand what was taking place there.
Yaakov lived his entire life in the shadow of the wicked brother, and although everyone recognized from their youth that this one was righteous and that one was wicked, Eisav would hide his actions in the cloak of righteousness. And while Yaakov sat in the yeshiva and engaged in Torah, Eisav would claim that this was not the correct way, and that one must also involve himself in matters of this world, for “If there is no flour, there is no Torah” (Avos 3:21). And as though for the sake of Heaven he would go out to the fields to hunt animals and satisfy his desires. But there was one great problem: Yaakov saw that Yitzchak – the great one of the generation – loved Eisav! Therefore, thoughts were overturned again and again in his mind: perhaps in truth Eisav is correct? Perhaps I also need to occupy myself a bit with matters of this world?
The “Or HaChaim HaKadosh” says that on that day Yaakov decided to change from his habit, and therefore he also tried to prepare foods for his father, and this is (25:29) ‘ויזד יעקב נזיד’ - “And Yaakov cooked a stew.” And when Hashem saw that “the power of endurance had weakened,” He caused Eisav to show his true face: “Pour into me now some of this red, red one,” so that Yaakov would see who Eisav truly was. Then Yaakov understood that his path was the correct one. But he needed to make for himself a sign so that he would remember these matters even when the tests would intensify: “Therefore he called his name Edom.”
It is written in the holy seforim that when a person reaches a clear recognition about a certain place or a certain person that they are not good for his spirituality, he should make a clear decision to distance himself. And even if the yetzer will attempt to come to him at another time to confuse him and dissuade him from his decision, he should respond to it that in this matter the decision was already made at an earlier time, and he does not wish to discuss it again. And it is better that he make for himself some sort of sign “in order to distance a person from sin” (Berachos 2a), exactly like Yaakov Avinu: “Therefore he called his name Edom.”