'Free will' in the Bible

But if the sacrifice of his oblation be a vow, or a freewill-offering, it shall be eaten on the day that he offers his sacrifice, and on the morrow that which remains of it shall be eaten,

And whoever offers a sacrifice of peace-offerings to LORD to accomplish a vow, or for a freewill-offering, of the herd or of the flock, it shall be perfect to be accepted; there shall be no blemish in it.

Either a bullock or a lamb that has anything superfluous or lacking in his parts, that thou may offer for a freewill-offering, but it shall not be accepted for a vow.

Besides the Sabbaths of LORD, and besides your gifts, and besides all your vows, and besides all your freewill-offerings, which ye give to LORD.