Exodus 4:10-17 (New International Version)

 ¹⁰ Moses said to the LORD, "O Lord, I have never been eloquent, neither in the past nor since you have spoken to your servant. I am slow of speech and tongue."

 ¹¹ The LORD said to him, "Who gave man his mouth? Who makes him deaf or mute? Who gives him sight or makes him blind? Is it not I, the LORD ? ¹² Now go; I will help you speak and will teach you what to say."

 ¹³ But Moses said, "O Lord, please send someone else to do it."

 ¹⁴ Then the LORD's anger burned against Moses and he said, "What about your brother, Aaron the Levite? I know he can speak well. He is already on his way to meet you, and his heart will be glad when he sees you. ¹⁵ You shall speak to him and put words in his mouth; I will help both of you speak and will teach you what to do. ¹⁶ He will speak to the people for you, and it will be as if he were your mouth and as if you were God to him. ¹⁷ But take this staff in your hand so you can perform miraculous signs with it."