11 And the Lord spoke to Moses, saying, 12 "Behold, I have taken the Levites from among the people of Israel instead of every firstborn who opens the womb among the people of Israel. The Levites shall be mine, 13 for all the firstborn are mine. On the day that I struck down all the firstborn in the land of Egypt, I consecrated for my own all the firstborn in Israel, both of man and of beast. They shall be mine: I am the Lord."
Matthew Henry's Commentary on Numbers 3:11-13
Commentary on Numbers 3:1-13
(Read Numbers 3:1-13)
There was much work belonging to the priests' office, and there were now only Aaron and his two sons to do it; God appoints the Levites to attend them. Those whom God finds work for, he will find help for. The Levites were taken instead of the first-born. When He that made us, saves us, as the first-born of Israel were saved, we are laid under further obligations to serve him faithfully. God's right to us by redemption, confirms the right he has to us by creation.