וְזָכַרְתִּ֣י אֶת־בְּרִיתִ֗י אֲשֶׁ֤ר בֵּינִי֙ וּבֵ֣ינֵיכֶ֔ם וּבֵ֛ין כָּל־נֶ֥פֶשׁ חַיָּ֖ה בְּכָל־בָּשָׂ֑ר וְלֹֽא־יִֽהְיֶ֨ה ע֤וֹד הַמַּ֙יִם֙ לְמַבּ֔וּל לְשַׁחֵ֖ת כָּל־בָּשָֽׂר׃
that I will remember My covenant, which is between Me and you and every living creature of all flesh; and the waters shall no more become a flood to destroy all flesh.
Zohar
"Yet trouble came." It was the trouble and confusion about Joseph, which was the hardest affliction of all. Why? Because Jacob loved Joseph, who is the secret of the Covenant through which Jacob entered Egypt. After this, it is written, "I remembered my covenant" (Beresheet 9:15), because the Shechinah was there with him, with the Covenant, who is Joseph. Thus, the confusion about Joseph was harder on him than all other afflictions that befell him.