Moses
Numbers 3:20ESV·traditional attribution

And the sons of Merari by their clans: Mahli and Mushi. These are the clans of the Levites, by their fathers’ houses.

Matthew Henry Presbyterian @wholebiblehenry

The Levites being granted to Aaron to minister to him, they are here delivered to him by tale, that he might know what he had, and employ them accordingly. Observe, I. By what rule they were numbered: Every male from a month old and upward, Num 3:15.

Commenting on Numbers 3:14-39

John Gill Reformed Baptist @doctorgill

And the sons, of Merari, by their families,.... The third son of Levi: Mahli and Mushi; the same as in Exo 6:19; from whom were denominated the families of the Mahlites and Mushites, who, as the preceding families, were numbered at this time: these are the families of the Levites, according to the house of their fathers; in all eight families.

Keil & Delitzsch Lutheran @keilanddelitzsch

Num 3:14-20 The muster of the Levites included all the males from a month old and upwards, because they were to be sanctified to Jehovah in the place of the first-born; and it was at the age of a month that the latter were either to be given up or redeemed (comp. Num 3:40 and Num 3:43 with Num 18:16).

Commenting on Numbers 3:14-20