Isaiah 28:24 - Ellicott's Commentary On The Whole Bible

Doth the plowman plow all day...? — Better, every day. Ploughing represents naturally, as in Jeremiah 4:3, the preparatory discipline by which the spiritual soil is rendered fit for the sower’s work. It is a means, and not an end, and is, therefore, in its very nature but for a season. To a nation passing through this stage, Assyrian invaders scoring their long furrows visibly on the surface of the land, the parable gave the hope that this was preparing the way for the seed-time of a better harvest.