Numbers 3

Numbers 3:7

And they shall keep his charge.

They shall do that service, which Aaron, as from the Lord, shall appoint unto them.

Numbers 3:9

Thou shalt give the Levites to Aaron and his sons.

Thou shalt design and appoint the Levites, to attend upon Aaron and his sons, in the holy ministration.

Numbers 3:12

I have taken the Levites from among the children of Israel instead of all the firstborn.

Whereas, before, the firstborn of the family was ordained to execute the office of the priesthood, and to offer sacrifices for the rest, now I have confined this office to one tribe alone; so as only those of Levi shall, instead of the firstborn, be set apart for this work.