and I say to you, “Let my son go that he may serve me.” If you refuse to let him go, behold, I will kill your firstborn son.’”
23. And I say unto thee, Let my son go. This was not the beginning of the legation, but its final clause; for Moses warned the desperate man of his son’s death, when everything else had been tried in vain. The meaning is, then, that the obstinacy of the tyrant must not prevent Moses from pressing him even to this final act.
Here, I. Moses obtains leave of his father-in-law to return into Egypt, Exo 4:18. His father-in-law had been kind to him when he was a stranger, and therefore he would not be so uncivil as to leave his family, nor so unjust as to leave his service, without giving him notice.
Commenting on Exodus 4:18-23
And I say unto thee, let my son go, that he may serve me,.... Worship God according to his will in the place he had designed for him, and where he might be safe and free; and which service was due from him as a son, and to be performed not in a servile way, but in a filial manner, and therefore as a servant...