Numbers 8:14

11 and Aaron hath waved the Levites -- a wave-offering before Jehovah, from the sons of Israel, and they have been -- for doing the service of Jehovah.

12 `And the Levites lay their hands on the head of the bullocks, and make thou the one a sin-offering, and the one a burnt-offering to Jehovah, to atone for the Levites,

13 and thou hast caused the Levites to stand before Aaron, and before his sons, and hast waved them -- a wave-offering to Jehovah;

14 and thou hast separated the Levites from the midst of the sons of Israel, and the Levites have become Mine;

15 and afterwards do the Levites come in to serve the tent of meeting, and thou hast cleansed them, and hast waved them -- a wave-offering.

16 `For they are certainly given to Me out of the midst of the sons of Israel, instead of him who openeth any womb -- the first-born of all -- from the sons of Israel I have taken them to Myself;

17 for Mine [is] every first-born among the sons of Israel, among man and among beast; in the day of my smiting every first-born in the land of Egypt I sanctified them for Myself;