Rashi

הכי קרא שמו IS IT BECAUSE HE HAS BEEN CALLED [JACOB]—This is a question, like (29:15) “Is it because (הכי) thou art my brother?” Perhaps that is why they have given him the name Jacob — in reference to what was to happen in the future — that he would some time or other supplant me (יעקבני)? (Tanchuma). Why did Isaac tremble? He thought: Perhaps I have sinned in blessing the younger before the elder, thus changing the order of relationship between them. But when Esau began to cry out, “for he hath supplanted me these two times”, his father asked him, “What did he do to you?” He replied, “He took away my birth-right”. Isaac thereupon said, “It was on account of this that I was grieved and trembled: perhaps I had overstepped the line of strict justice. Now, however, I have really blessed the first-born — ‘And he shall indeed be blessed’”. ויעקבני THAT HE HATH SUPPLANTED ME — Explain it as the Targum renders it, וחכמני, which means “and he lay in wait for me.” The word (Deuteronomy 19:11) וארב “and he lies in wait” is rendered by the Targum וכמי. There are some who read in the Targum not וכמני but וחכמני which means “he showed himself clever against me” (outwitted me). אצלת HAST THOU NOT RESERVED — the word means “separating״, “setting aside״, like (Numbers 11:25) “And he separated.