Moses
Deuteronomy 10:8ESV·traditional attribution

At that time the LORD set apart the tribe of Levi to carry the ark of the covenant of the LORD to stand before the LORD to minister to him and to bless in his name, to this day.

John Calvin Reformed @genevareformer

8. At that time the Lord separated the tribe of Levi Moses does not exactly observe the order of time in the chapter from which this passage is taken, since he deemed it sufficient to collect here and there what was required to complete his general exhortation.

Matthew Henry Presbyterian @wholebiblehenry

There were four things in and by which God showed himself reconciled to Israel and made them truly great and happy, and in which God's goodness took occasion from their badness to make him the more illustrious: - I. He gave them his law, gave it to them in writing, as a standing pledge of his favour.

Commenting on Deuteronomy 10:1-11

John Gill Reformed Baptist @doctorgill

At that time the Lord separated the tribe of Levi,.... Not at the time that Moses came down from the mount with the tables of the law, but some considerable time after, even after the tabernacle was erected; nor at the time that Aaron died, and Eleazar succeeded him, but many years before that; unless there was a fresh separation of them, or a renewal...