Musar for Sanhedrin 198:5

Torah study is also a preventative against one's coming to (speak) lashon hara, as they said there (Arachin 15b): "What is the preventative against lashon hara? If he is a Torah scholar, let him occupy himself with Torah." The reason is obvious, as we find in Sanhedrin 99b: "All men are created for toil, viz. (Iyyov 5:7): 'For man is born for toil.' I would not know whether for toil of the lips or toil of labor — if it were not written: (Mishlei 16:22): 'For he saddles his mouth with it,' which indicates that he was born for toil of the lips. And I still would not know whether for the [lip] toil of Torah or the toil of converse — if it were not written (Joshua 1:8): 'Let the book of this Torah not depart from your mouth,' which indicates that he was created for the toil of Torah." The idea is that the nature was given man, when speech was given to him, that the tools of speech do what is theirs without becoming fatigued, unlike the other organs, which man must spur himself to put into operation. Not so, the faculty of speech. And this is the intent of "the toil of the lips." But a man must reflect that this power was given him only to merit Torah. Therefore, it is stated that the preventative of speaking lashon hara is only occupying oneself with Torah, for lacking this, he will certainly stumble into forbidden speech. For it is man's nature that his tools of speech not be inoperative (unless he is able to overcome his yetzer and make himself "mute," as they say in Chullin 89a).

And man was created only for Torah. For thus have Chazal expounded (Sanhedrin 99b): "All men were created for toil, viz. (Iyyov 5;7): 'For man is born for toil.' I would not know whether for toil of the lips or toil of labor — if it were not written (Mishlei 16:26): 'For he saddles his mouth with it,' which indicates that he was born for toil of the lips. And I still would not know whether for the [lip] toil of Torah or the toil of converse — if it were not written (Joshua 1:8): 'Let the book of this Torah not depart from your mouth,' which indicates that he was created for the toil of Torah."

Chazal have said (Sanhedrin 99b): “All who study Torah for its own sake make peace in the celestial and terrestrial retinues, viz. (Isaiah 27:5): ‘Or if he but take hold of My stronghold [Torah], he shall make peace for Me [1]; he shall make peace for Me [2].’ Rav said: ‘It is as if he would build the celestial palace and the terrestrial palace, viz. (Ibid. 51:16): “And I have placed My words in your mouth … to plant the heavens and to lay the foundations of the earth.”’”