And Moses took with him the bones of Joseph, who had exacted an oath from the children of Israel, saying, “God will be sure to take notice of you: then you shall carry up my bones from here with you.”
It was Serach, the daughter of Asher, who told Moshe where Yosef was buried.
She was extremely old at the time and knew that the Egyptians put Yosef in a metal casket and placed it in the Nile River believing that doing so would bring blessing to the Nile.
Moshe went and stood on the bank of the Nile and said: “Yosef, Yosef, the time has arrived about which Hashem, took an oath saying that “I, will redeem you.” And the time for the fulfillment of the oath that you administered to the Jewish people, that they bury you in Eretz Yisrael has arrived. If you show yourself, good, but if not, we are exempt from your oath because we cannot be delayed.”
Immediately, the casket of Yosef floated to the top of the water.
Rabbi Natan says:
Yosef was buried in the crypt of the kings of Egypt. Moshe went and stood by the crypt and said the same statement. At that moment, the casket of Yosef shook among the caskets. Moshe then took it and went on his way.