24 Because I have given as a distinct portion to the Levites for an inheritance the tithes of the children of Israel, whatsoever they shall offer to the Lord; therefore I said to them, In the midst of the children of Israel they shall have no inheritance.
Numbers 18:24 Cross References - CAB
Numbers 18:26
26 You shall also speak to the Levites, and shall say to them, If you take the tithe from the children of Israel, which I have given you from them for an inheritance, then shall you separate from it a heave offering to the Lord, a tenth of the tenth.
Malachi 3:8-10
8 Will a man insult God? For you insult Me. But you say, How have we insulted You? In that the tithes and firstfruits are with you still.
9 And you do surely look off from Me, and you insult Me.
10 The year is completed, and you have brought all the produce into the storehouses; but there shall be the plunder thereof in its house: return now on this behalf, says the Lord Almighty, see if I will not open to you the torrents of heaven, and pour out My blessing upon you, until you are satisfied.