'Freewill Offering' in the Bible

The Israelites, all the men and women whose heart moved them to bring material for all the work which the Lord had commanded through Moses to be done, brought a freewill (voluntary) offering to the Lord.

They received from Moses all the offerings which the Israelites had brought for the construction of the sanctuary, to prepare it for service. And they continued to bring him freewill (voluntary) offerings every morning.