Matthew Henry Commentary Isaiah 28:23-29

"Give ye ear, and hear my voice; hearken, and hear my speech. Doth he that ploweth to sow plow continually? doth he [continually] open and harrow his ground? When he hath levelled the face thereof, doth he not cast abroad the fitches, and scatter the cummin, and put in the wheat in rows, and the barley in the appointed place, and the spelt in the border thereof? For his God doth instruct him aright, [and] doth teach him. For the fitches are not threshed with a sharp [threshing] instrument, neither is a cart wheel turned about upon the cummin; but the fitches are beaten out with a staff, and the cummin with a rod. Bread [grain] is ground; for he will not be always threshing it: and though the wheel of his cart and his horses scatter it, he doth not grind it. This also cometh forth from Jehovah of hosts, who is wonderful in counsel, and excellent in wisdom." — Isaiah 28:23-29 (ASV)

The farmer applies himself to his calling with diligence and prudence, in all its tasks according to their nature. Thus the Lord, who has given people this wisdom, is wonderful in counsel and excellent in His working.

As the occasion requires, He threatens, corrects, spares, shows mercy, or executes vengeance. Afflictions are God's threshing instruments, to loosen us from the world, to separate us from our chaff, and to prepare us for His use. God will proportion them to our strength; they shall be no heavier than necessary. When His purpose is accomplished, the trials and sufferings of His people shall cease; His wheat shall be gathered into the garner, but the chaff shall be burned with unquenchable fire.