Doth the plowman ... - The question here asked implies that he does “not” plow all the day. The interrogative form is often the most emphatic mode of affirmation.
All day - The sense is, does he do nothing else but plow? Is this the only thing which is necessary to be done in order to obtain a harvest? The idea which the prophet intends to convey here is this. A farmer does not suppose that he can obtain a harvest by doing nothing else but plow. There is much else to be done. So it would be just as absurd to suppose that God would deal with his people always in the same manner, as it would be for the farmer to be engaged in nothing else but plowing.
Doth he open ... - That is, is he always engaged in opening, and breaking the clods of his field? There is much else to be done besides this. The word ‘open’ here refers to the furrows that are made by the plow. The earth is laid open as it were to the sunbeams, and to the showers of rain, and to the reception of seed. The word rendered ‘break’ (ישׁדד yshadēd) properly means “to harrow,” that is, to break up the clods by harrowing Job 39:10; Hosea 10:11.