And Moses answered and said, But, behold, they will not believe me, nor hearken unto my voice: for they will say, The Lord hath not appeared unto thee. (4:1)

And Moses said unto the Lord, O my Lord, I [am] not eloquent, neither heretofore, nor since thou hast spoken unto thy servant: but I [am] slow of speech, and of a slow tongue. (4:10)

And he said, O my Lord, send, I pray thee, by the hand [of him whom] thou wilt send. (4:13)

And Moses spake before the Lord, saying, Behold, the children of Israel have not hearkened unto me; how then shall Pharaoh hear me, who [am] of uncircumcised lips? (6:12)