Says this:
24 At a lodging place on the way, the LORD met {Moses} and was about to kill him. 25 But Zipporah took a flint knife, cut off her son's foreskin and touched {Moses'} feet with it. "Surely you are a bridegroom of blood to me," she said. 26 So the LORD let him alone. (At that time she said "bridegroom of blood," referring to circumcision.)

It seems to be completely random. I can't figure out what it adds to the narrative or what the point of it is.

What do your commentaries say?