So he let him go. — God let Moses go, i.e., allowed him to recover — accepted Zipporah’s act as sufficient, albeit tardy, reparation, and spared the life of her husband.
Then she said. — When Moses was sufficiently recovered, Zipporah explained to him why she had called him “a bloody husband;” it was “on account of the circumcisions,” i.e., the two circumcisions — of Gershom in Midian, many years previously, and now of Eliezer. We learn from Exodus 18:2-3, that Zipporah and her boys were sent back to Jethro by Moses, probably at this time. Moses was in haste, and the child could not have travelled conveniently for some days.