Jacob regularly studied Torah with his sons. Judah was sent, even before Jacob’s descent to Egypt, to establish a study hall. The sign that Joseph sent to Jacob, so that his father would know that it was really he who sent the message that he was still alive, was based on their joint study.

“He sent Judah before him” (Genesis 46:28). The purpose of Jacob’s sending Judah was for Judah to prepare a study hall for him, so that he could issue rulings there and so that he could teach the tribes. Know that it is so that Jacob studied Torah with his children, as when Joseph went from him, Joseph knew which chapter Jacob was teaching him when he left him. When Joseph’s brothers came and said to Jacob: Joseph still lives, Jacob’s heart was faint because he did not believe them (see 45:26). Jacob said in his heart: I know that Joseph left me when we were studying the chapter of the calf [(Tanĥuma, Vayigash)