'Free will offerings' in the Bible

and hast brought in thither your burnt-offerings, and your sacrifices, and your tithes, and the heave-offering of your hand, and your vows, and your free-will offerings, and the firstlings of your herd and of your flock;

thou art not able to eat within thy gates the tithe of thy corn, and of thy new wine, and thine oil, and the firstlings of thy herd and of thy flock, and any of thy vows which thou vowest, and thy free-will offerings, and heave-offering of thy hand;