In the seventh aliyah, G-d says that the Leviim, like the Kohanim, won't receive a share of the land of Israel. Instead they will get the tithes of the other Jews. Furthermore, of this tithe that the Leviim receive from the Jewish people, the Leviim must, in turn, separate a tithe from it and give it to the Kohanim. The balance the Leviim keep as a wage for their service.