Exodus 7:12

9 If Pharaoh says to you, Let me see a wonder: then say to Aaron, Take your rod and put it down on the earth before Pharaoh so that it may become a snake.

10 Then Moses and Aaron went in to Pharaoh and they did as the Lord had said: and Aaron put his rod down on the earth before Pharaoh and his servants, and it became a snake.

11 Then Pharaoh sent for the wise men and the wonder-workers, and they, the wonder-workers of Egypt, did the same with their secret arts.

12 For every one of them put down his rod on the earth, and they became snakes: but Aaron's rod made a meal of their rods.

13 But Pharaoh's heart was made hard, and he did not give ear to them, as the Lord had said.

14 And the Lord said to Moses and Aaron, Pharaoh's heart is unchanged; he will not let the people go.

15 Go to Pharaoh in the morning; when he goes out to the water, you will be waiting for him by the edge of the Nile, with the rod which was turned into a snake in your hand;