'Freewill Offering' in the Bible

And whosoever remains in any place where he sojourns, let the men of his place help him with silver, and with gold, and with goods, and with animals, besides the freewill offering for the house of God that is in Jerusalem.

And afterward offered the continual burnt offerings, both of the new moons, and of all the set feasts of the LORD that were consecrated, and of every one that willingly offered a freewill offering unto the LORD.

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

And I said unto them, You are holy unto the LORD; the articles are holy also; and the silver and the gold are a freewill offering unto the LORD God of your fathers.