Exodus 6:29-30

Young's Literal Translation

²⁹ that Jehovah speaketh unto Moses, saying, `I [am] Jehovah, speak unto Pharaoh king of Egypt all that I am speaking unto thee.'

³⁰ And Moses saith before Jehovah, `Lo, I [am] of uncircumcised lips, and how doth Pharaoh hearken unto me?'