But Moses said to the LORD is almost identical with verse 12, where only a different word is used for said. The meaning is the same. Behold carries the same meaning as in verse 12. I am of uncircumcised lips means “I am such a poor speaker.” How then shall Pharaoh listen to me is a rhetorical question that means “Pharaoh certainly will not listen to me” (Translator’s Old Testament). (See 6.12 and comments.)

Quoted with permission from Osborn, Noel D. and Hatton, Howard A. A Handbook on Exodus. (UBS Helps for Translators). New York: UBS, 1999. For this and other handbooks for translators see here .