Exodus 4:11

7 “Put your hand back inside your cloak,” said the LORD. So Moses put his hand back inside his cloak, and when he took it out, it was restored, like the rest of his skin.

8 And the LORD said, “If they refuse to believe you or heed the witness of the first sign, they may believe that of the second.

9 But if they do not believe even these two signs or listen to your voice, take some water from the Nile and pour it on the dry ground. Then the water you take from the Nile will become blood on the ground.”

10 “Please, Lord,” Moses replied, “I have never been eloquent, neither in the past nor since You have spoken to Your servant, for I am slow of speech and tongue.”

11 And the LORD said to him, “Who gave man his mouth? Or who makes the mute or the deaf, the sighted or the blind? Is it not I, the LORD?

12 Now go! I will help you as you speak, and I will teach you what to say.”

13 But Moses replied, “Please, Lord, send someone else.”

14 Then the anger of the LORD burned against Moses, and He said, “Is not Aaron the Levite your brother? I know that he can speak well, and he is now on his way to meet you. When he sees you, he will be glad in his heart.

15 You are to speak to him and put the words in his mouth. I will help both of you to speak, and I will teach you what to do.

Read all of Exodus 4