Genesis 37:33

ויאמר כתנת בני AND HE SAID, MY SON’S COAT —is this (i.e. supply the words היא זו after בני). חיה רעה אכלתהו AN EVIL BEAST HATH EATEN HIM — The spirit of prophecy was enkindled within him, for these words may be taken to mean that at some future time Potiphar’s wife would attack him (Genesis Rabbah 84:19). Why did not the Holy One, blessed be He, make known to him (Jacob) that he was still living? Because they had placed under a ban and a curse anyone of them who would make it known, and they made the Holy One, blessed be He, a party with them to this agreement (Midrash Tanchuma, Vayeshev 2) Isaac, however, knew that he was living, but he thought, “How dare I reveal it since the Holy One, blessed be He does not wish to reveal it” (Genesis Rabbah 84:21).

וַיַּכִּירָ֤הּ וַיֹּ֙אמֶר֙ כְּתֹ֣נֶת בְּנִ֔י חַיָּ֥ה רָעָ֖ה אֲכָלָ֑תְהוּ טָרֹ֥ף טֹרַ֖ף יוֹסֵֽף׃

And he knew it, and said, It is my son’s coat; an evil beast has devoured him; Yosef is without doubt torn in pieces.