Moses answered, "What if they do not believe me or listen1 to me and say, 'The LORD did not appear to you'?"
References for Exodus 4:1
Then the LORD said to him, "What is that in your hand?" "A staff,"2 he replied.
References for Exodus 4:2
The LORD said, "Throw it on the ground." Moses threw it on the ground and it became a snake,3 and he ran from it.
References for Exodus 4:3
Then the LORD said to him, "Reach out your hand and take it by the tail." So Moses reached out and took hold of the snake and it turned back into a staff in his hand.
"This," said the LORD, "is so that they may believe4 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."
References for Exodus 4:5
Then the LORD said, "Put your hand inside your cloak." So Moses put his hand into his cloak, and when he took it out, the skin was leprous--it had become as white as snow.5
References for Exodus 4:6