21 And the Lord said to Moses, “When you go back to Egypt, see that you perform before Pharaoh all the wonders which I have put in your power; but I will harden his heart so that he will not let the people go. 22 Then you shall say to Pharaoh, ‘This is what the Lord says: “Israel is My son, My firstborn. 23 So I said to you, ‘Let My son go so that he may serve Me’; but you have refused to let him go. Behold, I am going to kill your son, your firstborn.” ’ ”
24 But it came about at the overnight encampment on the way, that the Lord met Moses, and sought to put him to death. 25 So Zipporah took a flint and cut off her son’s foreskin and threw it at Moses’ feet; and she said, “You are indeed a groom of blood to me!” 26 So He left him alone. At that time she said, “You are a groom of blood”—because of the circumcision.
Exodus 4:21–26 NASB
Leadership failure
Moses was neglectful in obeying the Hebrew covenant ritual of circumcision (his heart was hardened against God's command in a way similar to how Pharaoh's heart was hardened).
God called Moses on it.
Moses was deeply humiliated when his wife performed the task on his firstborn son.
Apparently the humiliation was strong enough that Moses and other son, Eliezer, were properly circumcised afterwards.
I'd guess that Moses would have liked to forget this episode; quite surprising that it was recorded.
Rob