Exodus 4:1, 10-13

And Moses answered and said, But, behold, they will not believe me, nor hearken unto my voice; for they will say, Jehovah hath not appeared unto thee.

And Moses said unto Jehovah, Oh, Lord, I am not eloquent, neither heretofore, nor since thou hast spoken unto thy servant; for I am slow of speech, and of a slow tongue. And Jehovah said unto him, Who hath made man’s mouth? or who maketh a man dumb, or deaf, or seeing, or blind? is it not I, Jehovah? Now therefore go, and I will be with thy mouth, and teach thee what thou shalt speak. And he said, Oh, Lord, send, I pray thee, by the hand of him whom thou wilt send.