Harsh words burn and scorch the very vitals, bones, heart, and the very sources of the life of men. Therefore, he that is virtuous, should always abstain from harsh and angry words. That worst of men is of harsh and wrathful speech, who pierceth the vitals of others with wordy thorns, beareth hell in his tongue, and should ever be regarded as a dispenser of misery to men.

In plain words: Harsh words burn a person deep inside, down to the heart and bones. So a good person avoids angry, cruel speech. Someone who wounds others with words is the worst kind of person and only spreads misery.