'Freewill Offering' in the Bible

Whoever is left, in any place where he lives, let the men of his place help him with silver, with gold, with goods, and with animals, besides the freewill offering for God's house which is in Jerusalem.'"

and afterward the continual burnt offering, the offerings of the new moons, of all the set feasts of the LORD that were consecrated, and of everyone who willingly offered a freewill offering to the LORD.

and all the silver and gold that you shall find in all the province of Babylon, with the freewill offering of the people, and of the priests, offering willingly for the house of their God which is in Jerusalem;

I said to them, "You are holy to the LORD, and the vessels are holy; and the silver and the gold are a freewill offering to the LORD, the God of your fathers.