Threshing was Performed by Instruments with Teeth
Source: TTT
Isaiah 41:15
Behold, I will make you into a threshing sledge, new and sharp, with many teeth. You will thresh the mountains and crush them, and reduce the hills to chaff.
Amos 1:3
This is what the LORD says: “For three transgressions of Damascus, even four, I will not revoke My judgment, because they threshed Gilead with sledges of iron.