Genesis 50:6

כאשר השביעך ACCORDING AS HE ADJURED THEE — For except for that oath I would not permit you to do so. He did not dare, however, to say to Joseph, “Break the oath”, lest he might retort, “Then, I, too, may break the oath I made you that I will never reveal that secret about the Sacred Tongue, viz., that I possess a knowledge of it in addition to the seventy languages which you also understand but of which you have no knowledge at all — as it is related in Treatise Sotah 36b.

וַיֹּ֖אמֶר פַּרְעֹ֑ה עֲלֵ֛ה וּקְבֹ֥ר אֶת־אָבִ֖יךָ כַּאֲשֶׁ֥ר הִשְׁבִּיעֶֽךָ׃

And Par῾o said, Go up, and bury thy father, according as he made thee swear.