'Free will' in the Bible

And will make an offering by fire to the LORD, a burnt-offering, or a sacrifice in performing a vow, or in a free-will-offering, or in your solemn feasts, to make a sweet savor to the LORD, of the herd, or of the flock:

These things ye shall do to the LORD in your set feasts, besides your vows, and your free-will-offerings, for your burnt-offerings, and for your meat-offerings, and for your drink-offerings, and for your peace-offerings.