Exodus 4:23
“And I say unto thee, Let my son go, that he may serve me: and if thou refuse to let him go, behold, I will slay thy son, even thy firstborn.”
And the Lord said unto Moses, When thou goest to return into Egypt, see that thou do all those wonders before Pharaoh, which I have put in thine hand: but I will harden his heart, that he shall not let the people go.
And thou shalt say unto Pharaoh, Thus saith the Lord, Israel is my son, even my firstborn:
And I say unto thee, Let my son go, that he may serve me: and if thou refuse to let him go, behold, I will slay thy son, even thy firstborn.
And it came to pass by the way in the inn, that the Lord met him, and sought to kill him.
Then Zipporah took a sharp stone, and cut off the foreskin of her son, and cast it at his feet, and said, Surely a bloody husband art thou to me.
Why This Verse Was Tagged
This verse was identified through meaning similarity — its content is mathematically close to known verses in this theme, even without sharing the same vocabulary.
Counter-Arguments
The strongest case that this verse does not belong in this theme.

Cross-References
“And it came to pass, that at midnight the Lord smote all the firstborn in the land of Egypt, from the firstborn of Pharaoh that sat on his throne unto the firstborn of the captive that was in the dungeon; and all the firstborn of cattle.”
“And it came to pass, that at midnight the Lord smote all the firstborn in the land of Egypt, from the firstborn of Pharaoh that sat on his throne unto the firstborn of the captive that was in the dungeon; and all the firstborn of cattle.”
“And all the firstborn in the land of Egypt shall die, from the firstborn of Pharaoh that sitteth upon his throne, even unto the firstborn of the maidservant that is behind the mill; and all the firstborn of beasts.”
“He smote also all the firstborn in their land, the chief of all their strength.”
“And smote all the firstborn in Egypt; the chief of their strength in the tabernacles of Ham:”