Kabbalah sur La Genèse 27:19

Rabbi Yitzchak said, Is it becoming for Jacob, who was holy, to say that he was defiled by Laban and his magic? Could it possibly be considered a credit to him to say, "I have sojourned with Laban?" Despite what Rabbi Yehuda said, that everything follows its own kind, Rabbi Yosi gave another explanation for the difficulty in that verse. It is written, "I am Esau your firstborn" (Beresheet 27:19). Here, we should ask, is it becoming to a righteous man such as Jacob to change his name to that of an impure one? The explanation is that under the "I," there is a tonal pause. Below the "I" is written the (tone) Pashta, whereas below "Esau, your firstborn," is found the (tone) Zakef Katon, whose tone separates the word "I" from "Esau your firstborn." What he actually said was "I am who I am, though Esau is your firstborn," as has already been explained.

"And he also had made savory food...Let my father arise" (Beresheet 27:31). His speech was impertinent, rough, and impolite. Come and behold the difference between Jacob and Esau. Jacob talked to his father humbly, with humility. It is written, "And he came to his father, and said, My father" (Ibid. 18). The difference between the language of Esau and Jacob is that Jacob did not want to frighten him. Thus, he spoke humbly, saying "arise, I pray you, sit and eat of my venison." Esau, however, said "Let my father arise," as if he was not speaking to him.