Exodus 7:10

7 Moses was eighty years old, and Aaron eighty-three years old, when they spoke to Pharaoh.

8 Yahweh spoke to Moses and to Aaron, saying,

9 "When Pharaoh speaks to you, saying, `Perform a miracle!` then you shall tell Aaron, `Take your rod, and cast it down before Pharaoh, that it become a serpent.`"

10 Moses and Aaron went in to Pharaoh, and they did so, as Yahweh 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. They also, the magicians of Egypt, did in like manner with their enchantments.

12 For they cast down every man his rod, and they became serpents: but Aaron`s rod swallowed up their rods.

13 Pharaoh`s heart was hardened, and he didn`t listen to them; as Yahweh had spoken.