Exodus 7:8

⁶  And Moses and Aaron did as the LORD 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 the LORD spake unto Moses and unto Aaron, saying,

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

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