How forcible are right words - A well-constructed argument, that has truth for its basis, is irresistible.
But what doth your arguing reprove? - Your reasoning is defective, because your premises are false; and your conclusions prove nothing, because of the falsity of the premises whence they are drawn. The last clause, literally rendered, is, What reproof, in a reproof from you? As you have proved no fault you have consequently reproved no vice. Instead of נמרצו מה mah nimretsu, "how forcible," נמלצו מה mah nimletsu, "how savoury or pleasant," is the reading of two MSS., the Chaldee, and some of the rabbins. Both senses are good, but the common reading is to be preferred.
How forcible are right words! - How weighty and impressive are words of truth! Job means that he was accustomed to feel their power, and to admit it on his soul. If their words were such, he would listen to them with profound attention, and in silence. The expression has a proverbial cast.
But what doth your arguing reprove? - Or rather, what doth the reproof from you reprove? or what do your reproaches prove? Job professes a readiness to listen to words of truth and wisdom; he complains that the language of reproach used by them was not adapted to instruct his understanding or to benefit his heart. As it was, he did not feel himself convinced, and was likely to derive no advantage from what they said.