Exodus 6:12; Exodus 6:30; Exodus 12:48

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?

Exodus 6:30

30 And Moses said before the LORD, Behold, I am of uncircumcised lips, and how shall Pharaoh hearken unto me?

Exodus 12:48

48 And when a stranger shall sojourn with thee, and will keep the passover to the LORD, let all his males be circumcised, and then let him come near and keep it; and he shall be as one that is born in the land: for no uncircumcised person shall eat thereof.