C. F. Keil and Franz Delitzsch on 2 Chronicles 31:4-10

2Ch 31:4-8

The priests and Levites received their maintenance from the first-fruits (Exo 23:19; Num 18:12; Deu 26:2) and the tithes, which the people had to pay from the produce of their cattle-breeding and their agriculture (Lev 27:30-33, cf. with Num 18:21-24). Hezekiah commanded the people, viz., the inhabitants of Jerusalem, to give this portion to the Levites and priests, that they might hold themselves firmly to the law of Jahve, i.e., might devote themselves to the duties laid upon them by the law, the attendance upon the worship, without being compelled to labour for their subsistence; cf. Neh 13:10.