On the night of the Exodus, while the entire nation of Israel was loading Egyptian gold and silver, Moses was doing something else. According to Sotah 13a, he was searching for the bones of Joseph.
Joseph had made the children of Israel swear an oath centuries earlier (Genesis 50:25): "God will surely visit you, and you shall carry my bones from here." The Israelites knew the oath. But no one knew where Joseph was buried. The Egyptians had sunk his coffin in the Nile to prevent the Israelites from ever leaving—or so they thought.
Serah bat Asher, a woman who had lived since the generation of Jacob, told Moses the location. He went to the banks of the Nile and called out: "Joseph, Joseph! The time has come for the oath you made Israel swear. If you show yourself, good. If not, we are released from the oath." The coffin rose from the water.
For the entire forty years in the wilderness, two arks traveled side by side: the Ark of the Covenant and the coffin of Joseph. Passersby would ask: "What are these two arks?" The answer: "One holds the dead, and one holds the Divine Presence. The dead one fulfilled everything written in the other." Joseph embodied every commandment in the Torah—he honored his parents, avoided adultery, did not steal, did not covet. His coffin deserved to travel alongside God's ark.
The eventual burial was in Shechem—the city from which his brothers had kidnapped him (Genesis 37:12). Rabbi Hama bar Hanina explained the poetic justice: "From Shechem they stole him, and to Shechem we return what was lost."
The Talmud asks: why did the children of Israel handle the burial rather than Joseph's own descendants? Because it was more honor for Joseph to be buried by the many than the few—and by Moses, the greatest of leaders, rather than by ordinary men.