Rashi on Genesis
ויעמוס איש על חמרו THEY LADED EVERY MAN HIS ASS — They were stalwart men and did not require the assistance of each other in loading (Genesis Rabbah 92:8).
Tur HaArokh
ויקרעו שמלותם, “they rent their garments, etc.” This was an illustration of the principle of מדה כנגד מדה, that the punishment fits the crime. The brothers having sent the blood-drenched coat of Joseph to their father at the time, had caused their father to rend his garments as a symbol of anguish and mourning. Now these same bothers had occasion to do the same.