'Free will offerings' in the Bible

and thither ye shall bring your burnt-offerings, and your sacrifices, and your tithes, and the heave-offering of your hand, and your vows, and your freewill-offerings, and the firstlings of your herd and of your flock:

Thou mayest not eat within thy gates the tithe of thy grain, or of thy new wine, or of thine oil, or the firstlings of thy herd or of thy flock, nor any of thy vows which thou vowest, nor thy freewill-offerings, nor the heave-offering of thy hand;