Charles Ellicott Commentary 2 Chronicles 31:3

"[He appointed] also the king`s portion of his substance for the burnt-offerings, [to wit], for the morning and evening burnt-offerings, and the burnt-offerings for the sabbaths, and for the new moons, and for the set feasts, as it is written in the law of Jehovah." — 2 Chronicles 31:3 (ASV)

He appointed also ... set feasts. —Rather, And the king’s portion (that is, the part he contributed) from his property was for the burnt offerings—namely, for the burnt offerings of the morning and the evening, and the burnt offerings on the Sabbath, and the new moons, the set feasts. The king gave the victims for the sacrifices prescribed in Numbers 28:29, out of his own revenues. See the account of his wealth (2 Chronicles 32:27–29). The “set feasts” were the three great festivals, and so on, enumerated in Numbers, in the place cited.