Uncircumcised lips - An uncircumcised ear is one that does not hear clearly; an uncircumcised heart one slow to receive and understand warnings; uncircumcised lips, such as cannot speak fluently. The recurrence of the hesitation of Moses is natural; great as was the former trial this was far more severe; yet his words always imply fear of failure, not of personal danger (see Exodus 3:11).
Related Commentaries of Exodus 6:12
Exodus 6:12
12 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?