Musar zu Mischlej 21:23

It is written (Proverbs 21:23), "One who keeps an eye on his mouth and tongue protects his life from trouble." In order to comprehend chaperoning the mouth and tongue and preventing life trouble which the Scripture defines, even more than all other ideas, that the perfect man needs to watch during the days, look in the basic commentaries. And I too shall speak over my part which Hashem has granted me, and with this we shall also understand that which is written (Psalms 34:13), "Whoever is a man who desires life and covets [his] days in order to perceive benevolence, shield your tongue from evil" etc.

Chazal have also been very specific in their holy language in the term "in this world" [("What is the craft of a man in this world? Let him make himself mute, etc.")] That is, let a man not think: "I have already been habituated to this ["muting"] for more years than a craftsman to his craft, and I no longer need to devote my eyes and my heart to it so much" — wherefore Chazal have taught us that this is not so; but a man must train himself in this craft of making himself a natural mute all the days of his life, as the GRA has written in Alim Litrufah: "And until the day of his death a man must chastise himself, not with fasts and mortifications, but by putting a rein to his mouth and his lusts. And this is tshuvah [repentance], and this is all the fruit of the world to come, as it is written (Mishlei 6:23): 'For a mitzvah is a lamp; and Torah, light, and the chastisements of mussar [moral discipline], the way of life.' This is [worth] more than all the fasts and mortifications in the world. And Scripture states (Psalms 34:13-15): 'Who is the man who desires life, who loves days to see good? Guard your tongue from evil, etc.' And in this way all of his sins will be forgiven and he will be saved from the depths of Sheol, as it is written (Mishlei 21:23): 'One who guards his mouth and his tongue guards his soul from suffering,' and (Ibid. 18:21): 'Death and life are in the power of the tongue.' Woe unto him who puts himself to death for one particle of speech. And what advantage is there to the man of the tongue?"

ענין מצורע . The affliction of a body with צרעת reflects that the soul has first been infected with spiritual blemishes. We know from the Zohar that the usual cause is abuse of one's power of speech.