TSK · Numbers 3:9

For they [are] wholly given unto me from among the children of Israel; instead of such as open every womb, [even instead of] the firstborn of all the children of Israel, have I taken them unto me.

And I have given the Levites [as] a gift to Aaron and to his sons from among the children of Israel, to do the service of the children of Israel in the tabernacle of the congregation, and to make an atonement for the children of Israel: that there be no plague among the children of Israel, when the children of Israel come nigh unto the sanctuary.

And I, behold, I have taken your brethren the Levites from among the children of Israel: to you [they are] given [as] a gift for the LORD, to do the service of the tabernacle of the congregation.

Then David said, None ought to carry the ark of God but the Levites: for them hath the LORD chosen to carry the ark of God, and to minister unto him for ever.

And they set the priests in their divisions, and the Levites in their courses, for the service of God, which [is] at Jerusalem; as it is written in the book of Moses.

Wherefore he saith, When he ascended up on high, he led captivity captive, and gave gifts unto men.