Exodus 14:19-20

19The angel of God had been leading the army of the Israelites. Now he moved and he went behind them. The pillar of cloud moved and it stood behind the army.

20It stood between the Egyptian army and the Israelite army. During the whole night, the Egyptians were in the dark, because of the cloud. But the cloud gave light to the Israelites. So the two armies did not come near to each other during the whole night.