Exodus
Chapters 6:27-30
Revised Version 1885
27These are they which spake to Pharaoh king of Egypt, to bring out the children of Israel from Egypt: these are that Moses and Aaron.
28And it came to pass on the day when the Lord spake unto Moses in the land of Egypt,
29that the Lord spake unto Moses, saying, I am the Lord: speak thou unto Pharaoh king of Egypt all that I speak unto thee.
30And Moses said before the Lord, Behold, I am of uncircumcised lips, and how shall Pharaoh hearken unto me?