Numbers 3:12-13

“Behold, I have taken the Levites from among the people of Israel instead of every first-born that opens the womb among the people of Israel. The Levites shall be mine, for all the first-born are mine; on the day that I slew all the first-born in the land of Egypt, I consecrated for my own all the first-born in Israel, both of man and of beast; they shall be mine: I am the LORD.”