Numbers 18:19
19 wAll the holy contributions that the people of Israel present to the Lord I give to you, and to your sons and daughters with you, as a perpetual due. xIt is a covenant of salt forever before the Lord for you and for your offspring with you.”
Numbers 18:26
26 “Moreover, you shall speak and say to the Levites, ‘When you take from the people of Israel the tithe that I have given you from them for your inheritance, then you shall present a contribution from it to the Lord, ga tithe of the tithe.
Numbers 18:29
29 Out of all the gifts to you, you shall present every contribution due to the Lord; from each its best part is to be dedicated.’