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.
ויראו אחי יוסף כי מת אביהם AND WHEN JOSEPH S BRETHREN SAW THAT THEIR FATHER WAS DEAD — What is the meaning of “and they saw”? They could perceive that he was dead through the conduct of Joseph. Previously they used to dine at Joseph’s table and he used to receive them with open arms out of respect to his father; after Jacob’s death, however, he no longer treated them in a friendly manner (Tanchuma Yashan 2:1:2; Genesis Rabbah 100:8).