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 the LORD.
The verse belongs to the reform of good King Hezekiah after images and idols were destroyed, when he appointed the priests and Levites to their respective offices and courses and restored temple worship and true religion. The king appointed from his own substance, resources and wealth what was required by the law of the LORD for the burnt offerings, for the morning and evening offerings and for the sabbaths, new moons and set feasts.
The phrase law of the LORD shows that the book of the law often called the law of Moses is also called the law of God, since the book contained the Ten Commandments and all laws given by God are God's laws, with their moral substance in the Decalogue. The sabbaths named in the verse are ceremonial festival sabbaths, distinct from the weekly Sabbath of the Lord.
Hezekiah commanded the people to give their portion to the priests and Levites so they could be encouraged in the law, and his own giving encouraged the people to contribute, so they obeyed at once by bringing in firstfruits, tithes and dedicated things until heaps accumulated over months. When questioned about the heaps, the answer was that the people had plenty to eat with much left over because the LORD had blessed His people, showing faithful giving brings bounteous store in harmony with the promise of blessing for bringing the tithe. The verse supports the Lord's claim to the tithe and the duty to give what belongs to Him. Giving to support worship as in the verse expresses willing, generous service to God.