The Hebrew verb adash means to tread out grain in the threshing process — having animals walk over cut stalks to separate grain from chaff. Part of the broad agricultural vocabulary rooting Israel's spiritual life in farming rhythms.
The threshing process described by adash is a recurring scriptural metaphor for divine judgment and purification. As animals tread grain to separate wheat from straw, God's judgments separate the righteous from the wicked. Isaiah 28 shows that God's discipline is calibrated and purposeful — He does not thresh grain forever.