As they lay on the shore in their last agony, they had to witness their own destruction and the victory of the Israelites, and they also beheld the suffering of their brethren that had remained behind in Egypt, for God poured out His punishment over the whole people, whether in Egypt or at the Red Sea. As for the corpses by the shores of the sea, they did not remain unburied, the earth swallowed them, by way of reward for Pharaoh's having acknowledged the justice of the chastisement that had been inflicted upon king and people.
Before their corpses had been disposed of in this way, there had been a quarrel between the earth and the sea. The sea said to the earth, "Take thy children unto thyself," and the earth retorted, "Keep those whom thou hast slain." The sea hesitated to do as the earth bade, for fear that God would demand them back on the day of judgement; and the earth hesitated, because it remembered with terror the curse that had been pronounced upon it for having sucked up Abel's blood.
Only after God swore and oath, not to punish it for receiving the corpses of the Egyptians, would the earth swallow them.