John Calvin Commentary Deuteronomy 10:8

"At that time Jehovah set apart the tribe of Levi, to bear the ark of the covenant of Jehovah, to stand before Jehovah to minister unto him, and to bless in his name, unto this day." — Deuteronomy 10:8 (ASV)

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. Indeed, the purpose of recounting this history was so that no one, in their pride and audacity, should attempt to overthrow God’s inviolable decree; and therefore, so that the dignity of the tribe of Levi would not give rise to envy, he testifies that God is its author. The clause, “to this day,” seems to refer to those instances in which God had manifested His favor towards the Levites, lest any similar rivalry should arise in the future. The rest has been expounded elsewhere.