Exodus 7:8

5 And the Egyptians shall know that I am Jehovah, when I stretch forth my hand upon Egypt, and bring out the children of Israel from among them.

6 And Moses and Aaron did so; as Jehovah commanded them, so did they.

7 And Moses was fourscore years old, and Aaron fourscore and three years old, when they spake unto Pharaoh.

8 And Jehovah spake unto Moses and unto Aaron, saying,

9 When Pharaoh shall speak unto you, saying, Show a wonder for you; then thou shalt say unto Aaron, Take thy rod, and cast it down before Pharaoh, that it become a serpent.

10 And Moses and Aaron went in unto Pharaoh, and they did so, as Jehovah had commanded: and Aaron cast down his rod before Pharaoh and before his servants, and it became a serpent.

11 Then Pharaoh also called for the wise men and the sorcerers: and they also, the magicians of Egypt, did in like manner with their enchantments.