Ex 4:24 And it came to pass on the way, at the encampment, that the LORD met him and sought to kill him.

25 Then Zipporah took a sharp stone and cut off the foreskin of her son and cast it at Moses' feet, and said, "Surely you are a husband of blood to me!"

26 So He let him go. Then she said, "You are a husband of blood!" -because of the circumcision.

In the meantime, there was an issue that was taking place in Moses' family. Moses delayed, to the point of disobedience, circumcising his son. It was apparently due to his wife's resistance of the rite. Moses did not act like the man of the house. And so, God was about to punish him. Seeing the direness of the situation, in order to save Moses' life, his wife was compelled to circumcise their son. 

Before we call on others to obedience we must be characterized by it first. Before we can go out and be used by God in public we must make sure first that we are obedient to God at home  

This is Moses' way of emphasizing the importance of keeping the covenant.