Exodus 4:3-5

4:3 The Lord said, “Throw it to the ground.” So he threw it to the ground, and it became a snake, and Moses ran from it. 4:4 But the Lord said to Moses, “Put out your hand and grab it by the tail” – so he put out his hand and caught it, and it became a staff in his hand – 4:5 “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.”

Exodus 4:8-9

4:8 “If they do not believe you or pay attention to the former sign, then they may believe the latter sign. 4:9 And if they do not believe even these two signs or listen to you, then take some water from the Nile and pour it out on the dry ground. The water you take out of the Nile will become blood on the dry ground.”