Charles Ellicott Commentary Exodus 6:12

"And Moses spake before Jehovah, saying, Behold, the children of Israel have not hearkened unto me; how then shall Pharaoh hear me, who am of uncircumcised lips?" — Exodus 6:12 (ASV)

How then will Pharaoh hear me? —This time the objection comes from Moses. His double rejection, by Pharaoh (Exodus 5:1–4) and by Israel (Exodus 6:9), had thrown him back into utter despondency. All that diffidence and distrust of himself which he had shown in his earlier communications with Jehovah (Exodus 3:11; Exodus 4:1; Exodus 4:10; Exodus 4:13) revived, and he despaired of success in his mission. Was there any use in his making a second appeal to the foreign monarch when he had failed with his own countrymen?

Uncircumcised lips. —Rosenmüller argues from this expression that Moses was “tongue-tied;” but it is not clear that more is meant here than in Exodus 4:10, where Moses says that he is slow of speech and of a slow tongue. He had some difficulty of utterance; but whether or not it was a physical impediment remains uncertain. “Uncircumcised” is used, according to the Hebrew idiom, for any imperfection which interferes with efficiency. An “uncircumcised ear” is explained in Jeremiah 6:10 to be an ear that cannot hearken; and an “uncircumcised heart” (Leviticus 26:41) is a heart that fails to understand.