'Free will offering' in the Bible

"If a person brings a peace offering sacrifice to the LORD to fulfill a vow or a free will offering from the herd or the flock, it is to be sound in order to be accepted, without any defect in it.

"You may offer a bull or lamb that has one limb longer than the other or that is stunted as a free will offering, but it's not acceptable in fulfillment of a promise.

With a free will offering I will sacrifice to you; I will give thanks to your name, LORD, because it is good,