The plowers plowed upon my back - The comparison here is undoubtedly taken from the “plowing” of land, and the idea is that the sufferings which they had endured were such as would be well represented by a plow passing over a field, tearing up the sod; piercing deep; and producing long rows or furrows. The direct allusion would seem to be to stripes inflicted on the back, as if a plow had been made to pass over it; and the meaning is, that they had been subjected to sufferings as slaves or criminals were when the lash cut deep into the flesh. Probably the immediate thing in the mind of the psalmist was the hard bondage of the children of Israel in Egypt, when they were subjected to all the evils of servitude.
They made long their furrows - On my back. The word used here, and rendered “made long” - ארך 'ârak means to make long, to prolong, to extend in a right line, and it may be used either in the sense of making long as to extent or space, or making long in regard to time, prolonging. The latter would seem to be the meaning here, as it is difficult to see in what sense it could be said that stripes inflicted on the back could be made long. They might, however, be continued and repeated; the sufferings might be prolonged sufferings as well as deep. It was a work of long-continued oppression and wrong.