Halakha Amsal 21:23: Mishneh Torah, Human Dispositions & Chafetz Chaim

But whosoever sits idle and takes no exercise, or who witholds eliminations of his bowels, or whose bowels are constipated, even though he will eat only good food and keep himself up after the prescribed medical rules, he will suffer pain all his life, and his strength will fade away. Ravenous eating is as deadly to the body of every man as poison, and is the base of all sickness; for, most diseases which visit man are not possible save either because of bad food, or because he fills up his bowels with overmuch food, even though the food be of good quality. Concerning this Solomon in his wisdom said: "Whoso guardeth his mouth and his tongue guardeth his soul against distresses" (Prov. 21.23), meaning, that whoso guards his mouth against bad food and ravenous eating, and his tongue from speaking aught but of the things he needs, guards his soul against distresses.

But this entire heter of two witnesses in the case of a man who is likely "to rule for himself" is of avail only to rescue them from the issur of forbidden speech; but, in any case they do not thereby leave the class of "abettors to the committers of transgression." For through them the hearer will [most likely] do something forbidden. For according to the din it is forbidden for him to accept their words and do something himself to cause loss to his friend so long as they have not testified in beth-din and beth-din have allowed him to do this, as explained above in Principle VI, sections 9 and 10. Aside from this, it is very difficult to conceive of this din arising in reality, to permit it in this case (aside from the fact that it is very rare for all of the [necessary] conditions to coincide). For it is hardly to be found that those who speak by themselves [and not in beth-din] know in the beginning all the aspects of the dinim in such an instance so as to assess that what Ploni will do to him because of their speaking will accord with the din of the Torah. Therefore, care must be taken not to reveal anything to a man whose nature is to "rule for himself" without the permission of beth-din, so that they not be entrapped through him in the snare of "the men of the tongue." And "He who guards his mouth and his tongue guards his soul from distress" (Proverbs 21:23).