And he slew it. — Better, and he killed, as the same word is rendered in the Authorised Version in Leviticus 8:19, that is, Moses killed it.
And put it upon the tip of Aaron’s right ear. — To teach him that, as the mediator between God and His people, it was his bounden duty to hearken to the commandments of the Lord.
And upon the thumb of his right hand. — To remind him that henceforth he is to execute God’s will, and walk in the way of His commandments.