Antiquities IV Chapter 4,3
3. And now Moses, because the tribe of Levi was made free from war and warlike expeditions, and was set apart for the Divine worship, lest they should want and seek after the necessaries of life, and so neglect the temple, commanded the Hebrews, according to the will of God, that when they should gain the possession of the land of Canaan, they should assign forty-eight good and fair cities to the Levites; and permit them to enjoy their suburbs, as far as the limit of two thousand cubits would extend from the walls of the city. And besides this, he appointed that the people should pay the tithe of their annual fruits of the earth, both to the Levites and to the priests. And this is what that tribe receives of the multitude; but I think it necessary to set down what is paid by all, peculiarly to the priests.