Compare Proverbs 10:6. Streams of living water (like the "fountain of living waters" of Jeremiah 2:13; Jeremiah 17:13, and the "living water" of John 4:10), flow from the mouth of the righteous, but that of the wicked is "covered," i. e., stopped and put to silence by their own violence.

The mouth of a righteous man is a well of life - מקור חיים mekor chaiyim, is the vein of lives; an allusion to the great aorta, which conveys the blood from the heart to every art of the body. The latter clause of this verse is the same with that of Proverbs 10:6.

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 good man's mouth is always open to teach, comfort, and correct others.

a well--or, "source" of good to himself and others (John 7:37-38). On last clause, see on Proverbs 10:6.

Another proverb, similar to the half of Proverbs 10:6 :
A fountain of life is the mouth of the righteous;
But the mouth of the godless hideth violence.
If we understand 11b wholly as 6b: os improborum obteget violentia, then the meaning of 11a would be, that that which the righteous speaks tends to his own welfare (Fl.). But since the words spoken are the means of communication and of intercourse, one has to think of the water as welling up in one, and flowing forth to another; and the meaning of 11b has to accommodate itself to the preceding half proverb, whereby it cannot be mistaken that חמס (violence), which was 6b subj., bears here, by the contrast, the stamp of the obj.; for the possibility of manifold windings and turnings is a characteristic of the Mashal. In the Psalm and Prophets it is God who is called מקור חיּים, Psalm 36:10; Jeremiah 2:13; Jeremiah 17:13; the proverbial poetry plants the figure on ethical ground, and understands by it a living power, from which wholesome effects accrue to its possessor, Proverbs 14:27, and go forth from him to others, Proverbs 13:14. Thus the mouth of the righteous is here called a fountain of life, because that which he speaks, and as he speaks it, is morally strengthening, intellectually elevating, and inwardly quickening in its effect on the hearers; while, on the contrary, the mouth of the godless covereth wrong (violentiam), i.e., conceals with deceitful words the intention, directed not to that which is best, but to the disadvantage and ruin of his neighbours; so that words which in the one case bring to light a ground of life and of love, and make it effectual, in the other case serve for a covering to an immoral, malevolent background.