Musar על עבודה זרה 37:20

And this is the intent of the verse (Koheleth 9:9): "See life with the woman that you love all the days of the life of your vanity, for that is your portion in life." "the woman that you love" alludes to Torah ["that you love" — for "one learns Torah only in the place (i.e., the subject) that his heart desires" (Avodah Zarah 19a)] And Scripture has exhorted us not to miss one day of Torah, for that is our portion in life. "your vanity" alludes to one who gives thought to himself to guard all of the days that he lives on the earth, not to waste one day, realizing that this world is a world of vanity, and that he has been sent here only to do the embassy of the Master of the world, to attain his portion in the Torah and in the fulfillment of mitzvoth in order to shine in the light of life in the world to come. About such a man we can hope that he will guard his days, that not one day will go to waste. In sum, just as the men of great wealth, who possess notes of great value, guard them vigilantly, each one of them representing a portion of their wealth, so, exactly, must the man of heart guard his days and hours, each of them being his portion in life. The maxim of the sage is well known: "There is no loss like the loss of time." For if a man loses a dinar from his pocket, he can hope to find it or that the Holy One Blessed be He will grant him a different one instead. But if a certain hour goes to waste, he will never find it again. And he will be made to face this when he comes for his accounting in time to come and they set out before him how he had spent his days and hours, as it is written (Psalms 50:21): "I shall reprove you; I shall set it out before your eyes." Chazal have said: "They illumine all of his deeds before him. Then he will bemoan himself over his conduct, but who will be able to help him then?" Happy is he who bethinks himself of all this while he yet lives!

Thus it was in the land of France that they occupied themselves with great industry and much time, and they would sit in one place to study all of the Talmud, and they would constantly review, and the Torah did not cease from their mouths. And they did according to the deeds of the earlier Sages, as they said, "Let one by all means learn, even though he is liable to forget, yea, even if he does not fully understand all of the words which he studies" (Abodah Zarah 19a). And they said, "That a man should study and subsequently understand." And all of this they do not do now, for everyone wants to study Tosafot, and new interpretations before he knows even the structure of the Talmud. This being the case, how can they make any progress? For they do the opposite of what the Sages of the Talmud said, for everything that is said in the Talmud is all true and one ought not to take issue with it or change it, nor add to it nor subtract from it.

The third element of repentance, that it be performed while a person is in his prime, when he is still subject to the temptation of the evil urge, is represented here by the tribe of Gad. The Mishnah in Avot 4,1, which describes a hero as a person who can conquer his passions, clearly shows that unless one has such passions, one does not qualify for the reward of having suppressed them. On Psalms 112,1, אשרי איש ירא את ה', "happy the man who fears the Lord," Rabbi Joshua ben Levi says that it refers to someone who does penitence while he is yet a man, in full possession of all his virility (Avodah Zarah 19a) [After all, why should a G–d-fearing woman not be described as happy? Ed.] The men of Gad were known as heroes. We know this from Genesis 49,19, when Jacob described him as turning the tables on any raiders. Compare Jerusalem Talmud Sotah 8,5. The heroism described there refers to his repentance, his sin having being due to his haste. Moses accused the members of that tribe by saying: "Shall your brothers go to war and you will sit it out here?" (Numbers 32,7) Note that although Gad was junior to Reuben, he was the first to make the request to stay in Trans-Jordan. Having been chastened by Moses, this tribe did more than it had been asked to do so as to compensate for its unbecoming conduct. This teaches that when repenting one should do so as wholeheartedly as the members of Gad and Reuven.