1 Corinthians 9:13-14

Know ye not that those who are occupied upon sacred things eat of the things of the temple? and that those who wait at the altar partake with the altar?

Galatians 6:6

But let him who is being taught in the word share with him who is teaching, in all good things.

Hebrews 7:5

And those, indeed, from among the sons of Levi, who receive the priesthood, have a commandment to take tithes of the people according to the law, that is, of their brethren, (though having come out of the loins of Abraham);

Treasury of Scripture Knowledge

Summary

And, behold, I have given the children of Levi all the tenth in Israel for an inheritance, for their service which they serve, even the service of the tabernacle of the congregation.

Bible References

Even the service

1 Corinthians 9:13
Know ye not that those who are occupied upon sacred things eat of the things of the temple? and that those who wait at the altar partake with the altar?
Galatians 6:6
But let him who is being taught in the word share with him who is teaching, in all good things.