'Freewill Offering' in the Bible

And Kore the son of Imnah the Levite, the gatekeeper toward the east, was over the freewill offerings of God, to distribute the sacrifices of Jehovah and the most holy things.

And whoever remains in any place where he resides, 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 they offered the continual burnt offering, both of the new moons and of all the set feasts of Jehovah that were set apart, and of everyone who willingly offered a freewill offering to Jehovah.