Isa. 28:24-29.

Plowing and harvesting are limited. The hardness of the soil governs the extent or intensity of the plowing. The type of grain determines the force and weight of the instruments used for threshing. Similarly, Jehovah God does not forever discipline or punish those who transgress his law. He disciplines them primarily to soften them, to make them more receptive to his counsel and guidance. This illustrates God’s wisdom in cleansing people, getting rid of undesirable traits by means of a treatment that best fits the existing needs.

For it is not with a threshing instrument that black cummin is given a treading; and upon cummin no wheel of a wagon is turned. For it is with a rod that black cummin is generally beaten out, and cummin with a staff.