John Gill Commentary 2 Chronicles 31:4

"Moreover he commanded the people that dwelt in Jerusalem to give the portion of the priests and the Levites, that they might give themselves to the law of Jehovah." — 2 Chronicles 31:4 (ASV)

Moreover, he commanded the people that dwelt in Jerusalem to give the portion of the priests and the Levites What was assigned unto them by the law of God by tithes, firstfruits

that they might be encouraged in the law of the Lord ; in the study of it; that they might gain greater knowledge of it themselves, and be better able to instruct the people, which of late had been much neglected; and that they might be more at leisure for such service, and be free from all worldly business, care, and distraction of mind, was the design of this edict.