פירוש על שמות 13:19

השבע השביע HE HAD STRAITLY ADJURED — He had made them swear that they would make their children swear. But why did he not make his sons swear that they would take him to the land of Canaan immediately on his death, as Jacob had made his sons swear? Joseph said: I was a ruler in Egypt and I had sufficient power to do what my father desired; but my sons — the Egyptians will not permit them to do this. Consequently he made them swear that when they would be delivered and would go forth from there that they would take him up with them (Mekhilta d'Rabbi Yishmael 13:19:8).

"And Moses took the bones of Joseph with him": this verse is juxtaposed to the previous verse "the jews ascended(Egypt) armed. because it states in the midrach Yalkut of this portion that the jews would journey in the desert with two arks, that of the ark of the Shechinah(the tablets of moses) and that of Joseph and the nations of the world would ask , what is the point of having this ark of joseph together with the ark of the coveneant and they would answer,"this one fulfilled what is in this one", for joseph fulfilled all the ten commandments etc.

ויקח משה את עצמות יוסף עמו, seeing that he was now the leader of the nation it was up to him to make good on the oath Joseph