Exodus 4:11

8 "It will happen, if they will neither believe you nor listen to the voice of the first sign, that they will believe the voice of the latter sign.

9 It will happen, if they will not believe even these two signs, neither listen to your voice, that you shall take of the water of the river, and pour it on the dry land. The water which you take out of the river will become blood on the dry land."

10 Moses said to Yahweh, "Oh, Lord, I am not eloquent, neither before now, nor since you have spoken to your servant; for I am slow of speech, and of a slow tongue."

11 Yahweh said to him, "Who made man`s mouth? Or who makes one mute, or deaf, or seeing, or blind? Isn`t it I, Yahweh?

12 Now therefore go, and I will be with your mouth, and teach you what you shall speak."

13 He said, "Oh, Lord, please send someone else."

14 The anger of Yahweh was kindled against Moses, and he said, "What about Aaron, your brother, the Levite? I know that he can speak well. Also, behold, he comes forth to meet you. When he sees you, he will be glad in his heart.