Abram was called Abraham, and Isaac was also called Abraham; as it is written (Gen. xxv. 19), "Isaac, Abraham's son, Abraham."
Ibid., chap. 63.
"And he lay down in that place" (Gen. xxviii. 11). Rabbi Yuda said, "There he lay down, but he did not lie down during all the fourteen years he was hid in the house of Eber." Rabbi Nehemiah said, "There he lay down, but he did not lie down all the twenty years in which he stood in the house of Laban."
Ibid., chap. 68.
Vayash Kihu, "And kissed him" (Gen. xxxiii. 4), Rabbi Yanai asks, "Why is this word (in the original Hebrew) so pointed?" "It is to teach that Esau did not come to kiss him, but to bite him; only the neck of Jacob our father became as hard as marble, and this blunted the teeth of the wicked one." "And what is taught by the expression 'And they wept'?" "The one wept for his neck and the other for his teeth."
Midrash Rabbah, chap. 78.
Rabbi Shimon ben Yochai in Sifri deliberately controverts this interpretation, and Aben Ezra says it is an "exposition fit only for children."
Esau said, "I will not kill my brother Jacob with bow and arrow, but with my mouth I will suck his blood," as it is said (Gen. xxxiii. 4), "And Esau ran to meet him, and embraced him, and kissed him, and they wept." Read not "and he kissed him," but read, "and he bit him." The neck of Jacob, however, became as hard as ivory, and it is respecting him that Scripture says (Cant. vii. 5), "Thy neck is as a tower of ivory,"—so that the teeth of Esau became blunted; and when he saw that his desire could not be gratified, he began to be angry, and gnashed his teeth, as it is said (Ps. cxii. 10), "The wicked shall see it and be grieved; he shall gnash with his teeth."
Pirke d'Rab. Eliezer, chap. 36.
See also the previous quotation from the Midrash Rabbah. The Targum of Jonathan and also the Yerushalmi record the same fantastic tradition. In the latter it is given thus, "And Esau ran to meet him, and hugged him, and fell upon his neck and kissed him. Esau wept for the crushing of his teeth, and Jacob wept for the tenderness of his neck."