'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 the house of God which is in Jerusalem.'"

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

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 Yahweh, and the vessels are holy; and the silver and the gold are a freewill offering to Yahweh, the God of your fathers.