What was the relationship between The Pharaoh of the Exodus and Aaron?
Aaron spoke to Pharaoh together with Moses. In front of Pharaoh, Aaron’s staff turned into a snake. Exodus 7:2, 10
What the Bible says
Exodus 7:2
Thou shalt speak to him all that I command thee; and he shall speak to Pharao, that he let the children of Israel go out of his land.
Exodus 7:10
So Moses and Aaron went in unto Pharao, and did as the Lord had commanded. And Aaron took the rod before Pharao, and his servants, and it was turned into a serpent.
Douay-Rheims Bible (Challoner revision), public domain.
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Meet The Pharaoh of the Exodus and Aaron.