The mouth of a righteous [man is] a well of life
Like a fountain of living water, continually running and flowing with water, wholesome, reviving, and refreshing; so the righteous man's mouth, out of the abundance of his heart, overflows with good things, which minister grace to the hearers, and are for the use of edifying; things that are pleasant and profitable, grateful and acceptable, comforting, refreshing, and pleasing, and which tend to the good of the life that now is, and that which is to come; but violence covereth the mouth of the wicked;
so that nothing comes out of it but what is pernicious and hurtful; what savours of rapine and violence; nothing but lying and deceit, cursing and swearing, and such like filthy and corrupt communication; (See Gill on Proverbs 10:6). The Targum is, "the mouth of the ungodly covers injury"; which is meditated in the heart; so the Vulgate Latin version.
The Brenton translation of the Septuagint is in the public domain.