John Calvin Commentary Exodus 14:26

"And Jehovah said unto Moses, Stretch out thy hand over the sea, that the waters may come again upon the Egyptians, upon their chariots, and upon their horsemen." — Exodus 14:26 (ASV)

And the Lord said to Moses. Moses here relates how the sea, in destroying the Egyptians, had no less obeyed God’s command than when it recently provided a passage for His people. For it was by the uplifting of Moses’ rod that the waters returned to their place, as they had previously been gathered in heaps.

The Egyptians now repented of their precipitate madness and, as conquered by God’s power, determined to leave the children of Israel and return home. But God, who willed their destruction, closed off their way of escape at this very crisis.

However, so that we may know how evident a miracle this was, Moses now adds the detail of the time. He says that the morning then appeared, so that broad daylight might reveal the whole event to the eyes of the spectators.

The waters, indeed, were piled up in the night; but the pillar of fire, which shone on the Egyptians and showed them their way, did not allow God’s blessing to be hidden from them.

The case of the Egyptians was different; therefore, it was fitting that they should perish by day, and that the sun itself should make their destruction visible.

This also tends to prove God’s power, because while they were trying to flee, He openly urged them on, as if they were intentionally drowning themselves.