Numbers 15:21
Some of the first of your dough you shall give to the LORD as a contribution throughout your generations.
Exodus 29:28
It shall be for Aaron and his sons as a perpetual due from the people of Israel, for it is a contribution. It shall be a contribution from the people of Israel from their peace offerings, their contribution to the LORD.
Numbers 18:26
"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, a tithe of the tithe.