Musar su Proverbi 6:23

How pleasant is the Musar of Love. Anyone whom Hashem loves, God brings down upon them suffering. You find three good gifts that God gave to Israel; and they were only given by way of suffering. These are them: Torah, the Land of Israel, and the World to Come.

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?"

And we find in Midrash Tehillim 49:2: "'To the chief musician, to the sons of Korach, a psalm.' This is as Scripture says (Koheleth 11:7): 'And sweet is the light, and good for the eyes.' How sweet is the light of the world to come. Happy is the man who has the good deeds to see that light, as it is written (Judges 5:31): 'And His lovers [will be] as the rising of the sun in his might.'" R. Abba said: "How sweet are those things which are compared to light. As it is written (Mishlei 6:23): 'For a mitzvah is a lamp, and Torah, light, etc.' Happy is the man who sees the Torah white as snow, for there is no end to its reward. When the Holy One Blessed be He will come to pay Israel the reward of the toilers in Torah and will bestow upon them of the secreted light in its merit — at that time they will say to the peoples of the world: 'We merited [this] because we occupied ourselves with Torah. And you used to say to us: "You are wearying yourselves for nothing." — See its reward!' As it is written (Psalms 49:2): 'Hear this [zoth] all you people.' And 'zoth' is the Torah.' (Psalms, Ibid.): 'Hear, all you dwellers of the earth [chaled]' — these are the men who raise rust [chaludah] in Gehinnom. And who are they? (Ibid. 3): 'Both the sons of "Adam" and the sons of "Ish."' "Adam" — this is Abraham, viz. (Joshua 14:15): 'the great man [Adam] among the giants.' Also the sons of Adam' — Yishmael and the sons of Ketura. 'Also the sons of Ish' — the sons of Noach, who was called ish tzaddik (Bereshith 6:9). Another interpretation: These are the idolators, who descend to Gehinnom. (Ibid.): "rich and poor together" — rich in Torah and poor in Torah. "rich" — Doeg and Achitophel. Even though they were heads of sanhedrin, they descended to Gehinnom. "and poor in Torah" — one who can learn but does not learn. Therefore, the sons of Korach said (Ibid. 4): 'My mouth shall speak wisdom' — the wisdom of Torah; 'and my heart shall meditate understanding' — the understanding of Torah. (Ibid. 5) 'I will incline my ear to a parable' — the parable of Torah." And this is the language of the holy Zohar, Parshath Vayeshev:"