Jacob desired not to be buried in Egypt for several reasons. He knew that the soil of Egypt would once swarm with vermin, and it revolted him to think of his corpse exposed to such uncleanness. He feared, moreover, that his descendants might say, "Were Egypt not a holy land, our father Jacob had never permitted himself to be buried there," and they might encourage themselves with this argument to make choice of Egypt as a permanent dwelling-place.
Also, if his grave were there, the Egyptians might resort to it when the ten plagues came upon them, and if he were induced to pray for them to God, he would be advocating the cause of the Lord's enemies. If, on the other hand, he did not intercede for them, the Name of God would be profaned among the heathen, who would say, "Jacob is a useless saint!" Besides, it was possible that God might consider him, the "scattered sheep" of Israel, as a sacrifice for the Egyptians, and remit their punishment.
From his knowledge of the people, another fear was justified, that his grave would become an object of idolatrous veneration, and the same punishment is appointed by God for the idols worshipped as for the idolaters that worship them.