“As soon as I leave you,” Moses said, “I will pray to the LORD, so that tomorrow the swarms of flies will depart from Pharaoh and his officials and his people. But Pharaoh must not act deceitfully again by refusing to let the people go and sacrifice to the LORD.”
29. And Moses said, Behold I go out from thee. Moses does not reply to this demand, because he knew that the design of God was otherwise; and God had justly left him in ignorance as to what He did not yet wish him to know.
Here is the story of the plague of flies, in which we are told, I. How it was threatened, like that of frogs, before it was inflicted. Moses is directed (Exo 8:20) to rise early in the morning, to meet Pharaoh when he came forth to the water, and there to repeat his demands. Note, 1.
Commenting on Exodus 8:20-32
And Moses went out from Pharaoh, and entreated the Lord. He did as he promised he would, and prayed to the Lord to remove the flies from Pharaoh and his people. And Moses went out from Pharaoh, and entreated the Lord. He did as he promised he would, and prayed to the Lord to remove the flies from Pharaoh and his people.