Shemirat HaLashon שמירת הלשון

Now we shall explain the greatness of the merit of one who guards his mouth and his tongue from speaking forbidden things. First, he amends and sanctifies thereby the distinctive "tool" of the Jew, which is speech. So that all the words that he speaks thereafter in Torah and in prayer ascend to the source of its root on high. For not in vain did Chazal compare this [faculty] in many places to a "tool of the trade" [see Rashi, Bamidbar 31:8], to teach us that just as a tool is necessary for the making of new, beautiful vessels, [so is it with the "tool" of speech]. Even if one be the king's craftsman, the greatest of all the artists, whose intellect is extremely subtle, and who can conceive of the finest way of fashioning vessels, still, he cannot make them without tools. And, more than this, even if he has the tools, but they are defective and damaged, and he is "pressured" to make some vessels, there will be recognized through them the defect and the imperfection of the tools, inside and outside, because he will not be able to smooth them [the vessels] out correctly and they will remain like formless blocks of wood, unfit for use even by commoners; how much more so, for a king. But that craftsman whose tools are polished and shined as they should be — the vessel that he fashions with them will emerge perfect and beautiful. It is exactly the same with the faculty of speech given to the Jew for the service of the awesome King (blessed be His name) for Torah and prayer, and for blessing, glorifying, praising, and exalting Him. For it [(this faculty)] is the great tool whereby the complete man can build heaven and earth, as it is written (Isaiah 51:6): "And I have placed My words in your mouth to plant the heavens and to lay the foundations of the earth." And this is to be understood literally. For with the words of holiness that a man speaks here in this world before the blessed L-rd, there are created on high holy worlds and angels, who will afterwards be protagonists for and defenders of his soul. And the quality of the worlds and the angels created through his Torah and mitzvoth depend on several factors: 1) his mind-set at the time. That is, his having readied himself at that time with all his powers to fulfill his task according to the Torah, in all of its requisite parts and details. 2) his tools, by which his Torah is fashioned. That is, the tools of speech (and, likewise, in respect to the mitzvah, the tools required to execute it.) For if they are beautiful and elegant, being used always for the good, and the power of their sanctity being thereby strengthened, they will have the power to draw down the higher sanctity and great light on whatever he is doing. But if he renders defective and unclean, G-d forbid, his faculty of speech through lashon hara, rechiluth, levity, and falsity, and the like, and he does not repent, and then he speaks with his mouth words of Torah and prayer, what power will they have to draw down on that Torah and prayer the higher sanctity after his "tools of utterance" have been rendered defective and unclean in and of themselves?

And Chazal have said (Shabbath 119b): "The breath of the mouth that has sinned is not like the breath of the mouth that has not sinned." ["the breath of the mouth that has sinned":] That is, he who has sinned only sometimes, by chance, as we have explained in Chapter VII. How much more so if the breath of his mouth is habituated to sin every day and every hour. And all this, even if his mouth sins in other forbidden things; how much more so, in the issur of lashon hara and rechiluth by which he certainly undermines the prayer that he prays after this; and it does not ascend unless he undertakes to repent of this, as we explained above in Chapter VII in the name of the holy Zohar. And we can say that this is the intent of the verse in Koheleth 7:13: "See the act of G-d. For who can straighten out what he has made crooked?" That is, set your eyes and your heart on the G-dly things, the holy sanctuaries and the celestial lights created by you on high by your Torah and your mitzvoth — that they be created in perfection, by all the preparations needed for this and also by "clean tools," as explained above. For who can straighten out what he has made crooked? This is, if you damage them, G-d forbid, they will remain forever defective and damaged, and this will cause you eternal worry and constant grief in remembering that it was your slothfulness that caused all this. For they [(the heavenly edifices)] are not like the buildings of this world, which, if one damages them, another builder can repair them. Not so, with the desired [eternal] end. As stated by the tanna in Avoth 1:13: "If I am not for myself, who is for me?" And this is the intent of the verse "For who can straighten out what he has made crooked?"

What follows from all we have said is that by guarding his tongue according to the din, a man merits sanctifying his faculty of speech, and, thereby, his Torah and his prayer will be accepted on high.