Musar su Genesi 49:5

When people pronounce a ban, חרם, on someone or something, they have to be most circumspect even when the ban is in itself of a forbidden nature. One needs to be even more careful when one places someone in a ban in consequence of a permissible legal proceeding. We can examine and learn from the extreme caution practised by Joseph's brothers who entered into a conspiracy of silence not to reveal what had happened to Joseph. The secret was therefore kept. Even G–d Himself did not reveal the secret; the brothers had included Him in those upon whom the vow of silence was imposed. It was only shortly before Jacob's death, when the latter reproved his sons and blessed them, that The Holy Spirit revealed to Jacob what had transpired, so that Jacob might be able to admonish his sons prior to his death. During these blessings, Jacob referred pointedly to Shimon and Levi's part in the maltreatment of Joseph (Genesis 49,6 "they tried to uproot the ox"). When a person is close to death, it is time for him to dispense admonitions as well as blessings. Joseph never told his father that his brothers had sold him.