Exodus 4:1-6 RSV

1 Then Moses answered, "But behold, they will not believe me or listen to my voice, for they will say, 'The LORD did not appear to you.'"
2 The LORD said to him, "What is that in your hand?" He said, "A rod."
3 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.
4 But the LORD said to Moses, "Put out your hand, and take it by the tail" --so he put out his hand and caught it, and it became a rod in his hand--
5 "that they may believe that the LORD, the God of their fathers, the God of Abraham, the God of Isaac, and the God of Jacob, has appeared to you."
6 Again, the LORD said to him, "Put your hand into your bosom." And he put his hand into his bosom; and when he took it out, behold, his hand was leprous, as white as snow.