'Threshing' in the Bible

While Ornan was threshing wheat, he turned and saw the messenger, and he and his four sons hid themselves.

Ornan told David, "You can have it! My master, the king, may do what he wants. Look, I am giving you the oxen for burnt sacrifices, the threshing sledges for wood, and the wheat for an offering. I give it all to you."