Matthew Henry Presbyterian @wholebiblehenry

Here is the exchange made of the Levites for the first-born. 1. The first-born were numbered from a month old, Num 3:42, Num 3:43. Those certainly were not reckoned who, though first-born, had become heads of families themselves, but those only that were under age; and the learned bishop Patrick is decidedly of opinion that none were numbered but those only that were born since...

Commenting on Numbers 3:40-51

John Gill Reformed Baptist @doctorgill

Take the Levites instead of all the firstborn among the children of Israel,.... The Lord had declared before that he had taken them, and now he bids Moses take them, who had numbered them, and give them to Aaron, instead of the firstborn, whose numbers were also taken for this purpose: and the cattle of the Levites instead of their cattle; but not to be...

Keil & Delitzsch Lutheran @keilanddelitzsch

Num 3:40-48 After this, Moses numbered the first-born of the children of Israel, to exchange them for the Levites according to the command of God, which is repeated in Num 3:41 and Num 3:44-45 from Num 3:11-13, and to adopt the latter in their stead for the service at the sanctuary (on Num 3:41 and Num 3:45, cf. Num 3:11-13).

Commenting on Numbers 3:40-48