Musar על עירובין 107:31

Always focus your attention on these matters and not on others, because all else is trivial. For man can salvage nothing from his labor to take with him (see Koheles 5:14), except two white garments (shrouds). Also (Tehillim 49), "A man will not redeem his brother...Fear not when a man grows rich...For when he dies, he shall carry nothing away...." Don't say, "I will leave a portion for my children" - who will tell you in the grave? The children of man are like grasses of the field, some blossom and some fade (Eruvin 54a). Everyone is born under his constellation and Divine Providence. They are glad when he dies and he goes into the nether world. [At his death] Resh Lakish left his children a kav of saffron, and he applied to himself the verse (Tehillim 49:11), "...and they leave their wealth to others" (Gittin 47a). Woe to all who plan on leaving [wealth] to their children! The only reward from sons and daughters is through their Torah and good deeds. Their sustenance is fixed for them. It is also known that women earn merit by making their children learn Torah etc. (Berachos 17a)

The reason is obvious: Speech is not a specific part of a man as his other limbs are, each one being of benefit in itself. But it is the generality of man and his completeness. And that is why, when he perfects himself by occupying himself with Torah, all of his limbs are amended. For it reposes upon them a spirit of holiness to vivify them and to sustain them in this world and the next. As Chazal have said: "If one's head ails him, let him study Torah, as it is written, etc. If his throat ails him, let him study Torah, etc. If his whole body ails him, let him study Torah, as it is written (Mishlei 4:22): 'And to all his flesh it is healing.'" And the opposite, G-d forbid — by forbidden speech, he harms and defiles all of his limbs, and each and every limb falls from its eminence through this. And what advantage is it to them that their master lives and speaks if only to render din and accounting!

A piece of good advice for guarding the tongue: Even if he has already become habituated to it [(i.e., to a certain kind of lashon hara)], G-d forbid, and his yetzer has overcome him in this area, so that he himself does not "feel" the lashon hara that issues from his mouth, still he should not despair, but he should rest assured that by reviewing the din several times, a transformation will take place and the thing [i.e., the din] will become fixed in his nature, and, in the end he will "feel" [i.e., he will be sensitive to] every [article of] speech that leaves his mouth; and even if it be only the "dust" of lashon hara, he will feel it with his tongue at that time. For the Holy One Blessed be He has implanted in a man the faculty of "feeling" [i.e., sensitivity]. And He has done it in such a way that he feels it more when the "thing" comes in contact with his tongue. (This is similar to what Chazal have said (Chullin 17b): "The master examined it [(the slaughtering knife for kashruth)] with his mouth.,") And this faculty is of great avail in the learning of Torah, so that when one brings the thing [(what he is learning)] from his mouth to his tongue, its correctness is "tested." As Chazal have said (Eruvin 54a) on Mishlei 4:22: "For they [(words of Torah)] are life lemotzeihem"… to those who utter them ['lemotzi'eihem'], with their mouths." And the same [phenomenon] holds true for all aspects of speech; but it is only because of his great habituation to superfluous speech and [his tendency] to pay no heed to it that this faculty of his has become greatly weakened. But if he follows our advice (And he certainly will be attentive to what he says from that time on), this faculty of feeling will gradually strengthen itself in him, little by little until it reaches ifs full development.

CLINGING: The matter of clinging is when a person's heart clings so much to the blessed G-d that he ceases to turn or take interest in anything else but Him. This is what Shlomo brought by way of analogy: "a lovely hind and a graceful doe, her breasts will satisfy you at all times; you shall always be infatuated with her love" (Mishlei 5:19). And in the Talmud, our sages, of blessed memory stated (Eruvin 54b): "It was said of Rebbi Eliezar ben Pedat that he sat and studied Torah in the lower market of Tzipori while his cloak lay in the upper market of the town". The ultimate goal of this trait is for a person to cling thus to His Creator at all times, and at every moment. But at the least, if he loves his Creator, certainly he will cling to Him in this manner during the times of his [divine] service.