Numbers 3:45Meaning & Commentary from the Church Fathers

It should be observed that all the firstborn of Israel, who were born from the time the law regarding firstborns was established (see Ex. 10:42), are now for the first time supplanted by the Levites, with the redemption occurring only for the surplus, which amounts to 273 newborns. From this point on, the tribe of Levi, consecrated to the Lord, along with all its descendants, is wholly devoted to Jehovah and cannot act as a substitute for the firstborn, who are governed by the statutes detailed in the writings of Exodus (Ex. 13:2, 12), Leviticus (Lev. 27:6), and Numbers.