Exodus 4:1-4

Then Moses answered and said, “But suppose they will not believe me or listen to my voice; suppose they say, ‘The LORD has not appeared to you.’ ” So the LORD said to him, “What is that in your hand?” He said, “A rod.” And He said, “Cast it on the ground.” So he cast it on the ground, and it became a serpent; and Moses fled from it. Then the LORD said to Moses, “Reach out your hand and take it by the tail” (and he reached out his hand and caught it, and it became a rod in his hand)