Exodus 4:3-5

“Throw it down on the ground,” the LORD told him. So Moses threw down the staff, and it turned into a snake! Moses jumped back. Then the LORD told him, “Reach out and grab its tail.” So Moses reached out and grabbed it, and it turned back into a shepherd’s staff in his hand. “Perform this sign,” the LORD told him. “Then they will believe that the LORD, the God of their ancestors—the God of Abraham, the God of Isaac, and the God of Jacob—really has appeared to you.”