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

12 But Moses spoke before the LORD , saying, "Behold, the sons of Israel have not listened to me; how then will Pharaoh listen to me, for I am unskilled in speech?"
30 But Moses said before the LORD , "Behold, I am unskilled in speech; how then will Pharaoh listen to me?"
48 "But if a stranger sojourns with you, and celebrates the Passover to the LORD , let all his males be circumcised, and then let him come near to celebrate it; and he shall be like a native of the land. But no uncircumcised person may eat of it.