John Calvin on Leviticus 9:6

6. And Moses said, This is the thing which the Lord commanded He seems, indeed, to address himself to the whole people, to whom also the promise belonged; but in the word “do ye,” “That ye should do.” — A. V. He specially speaks to the sons of Aaron; and he promises what, at the end of the chapter, he will state to have been fulfilled, that the glory of God should be manifested in approbation of the priesthood, in order that they may set about their duties more cheerfully. For this was no common aid to their faith and assurance, that their office should be thus, as it were, sealed by God.