Exodus 4:24 - Wesley's Explanatory Notes

It seems the sin of Moses, was neglecting to circumcise his son, which perhaps was the effect of his being unequally yoked with a Midianite, who was too indulgent of her child, and Moses so of her. The Lord met him, and, probably, by a sword in an angel's hand, sought to kill him — This was a great change. Very lately God was conversing with him as a friend, and now coming forth against him as an enemy. In this case of necessity Zipporah herself circumcised the child without delay; whether with passionate words, expressing the dislike of the ordinance itself, or at least the administration of it to so young a child.