Greetings everyone,
Consider with me the following scripture: Leviticus 22:29 - And when ye offer a sacrifice of thanksgiving unto the LORD, offer it at your own will. How about that? In Old Testament times a sacrifice could be offered up to God by an Israelite as an act of sheer gratitude. Note that this was not necessarily a corporate sacrificial offering, but that it could be offered individually. Just out of pure recognition of God, clothed with sincere gratefulness- this sacrifice was offered. In modern day church colloquialism we'd call it a type of 'free will' offering.
When you get a moment, take a look at the thanksgiving offering in the book of Leviticus. It is discussed primarily in chapters 3, 7, and 22. For in-depth study purposes, note that it falls under the category of a type 'peace offering'.
In His Service,
DsW