1. They must do by their hearts as they do by their ground that they expect any good of; they must plough it up (v. 3): "Break up your fallow-ground. Plough to yourselves a ploughing (or plough up your plough land), that you sow not among thorns, that you may not labour in vain, for your own safety and welfare, as those do that sow good seed among thorns and as you have been doing a great while. Put yourselves into a frame fit to receive mercy from God, and put away all that which keeps it from you, and then you may expect to receive mercy and to prosper in your endeavours to help yourselves." Note, (1.) An unconvinced unhumbled heart is like fallow-ground, ground untilled, unoccupied. It is ground capable of improvement; it is our ground, let out to us, and we must be accountable for it; but it is fallow; it is unfenced and lies common; it is unfruitful and of no advantage to the owner, and (which is principally intended) it is overgrown with thorns and weeds, which are the natural product of the corrupt heart; and, if it be not renewed with grace, rain and sunshine are lost upon it, Heb. vi. 7, 8. (2.) We are concerned to get this fallow-ground ploughed up. We must search into our own hearts, let the word of God divide (as the plough does) between the joints and the marrow, Heb. iv. 12. We must rend our hearts, Joel ii. 13. We must pluck up by the roots those corruptions which, as thorns, choke both our endeavours and our expectations, Hos. x. 12.