exodus 6:12 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? - Free Bible Online

      12. how then shall . . . who am of uncircumcised lips?--A metaphorical expression among the Hebrews, who, taught to look on the circumcision of any part as denoting perfection, signified its deficiency or unsuitableness by uncircumcision. The words here express how painfully Moses felt his want of utterance or persuasive oratory. He seems to have fallen into the same deep despondency as his brethren, and to be shrinking with nervous timidity from a difficult, if not desperate, cause. If he had succeeded so ill with the people, whose dearest interests were all involved, what better hope could he entertain of his making more impression on the heart of a king elated with pride and strong in the possession of absolute power? How strikingly was the indulgent forbearance of God displayed towards His people amid all their backwardness to hail His announcement of approaching deliverance! No perverse complaints or careless indifference on their part retarded the development of His gracious purposes. On the contrary, here, as generally, the course of His providence is slow in the infliction of judgments, while it moves more quickly, as it were, when misery is to be relieved or benefits conferred.

JFB.