Why does the Talmud state one *can* regret his mitzvos (good deeds) and lose them? If regretting one’s sins is only effective due to G-d’s special mercy, why would He allow the same for one who regrets his mitzvos? Is G-d extending an especial *cruelty* to allow it? We can appreciate that G-d is merciful and may extend an especial kindness, allowing us to regret our sins, but the Talmud appears to state G-d does the same for one who regrets his mitzvos. Why would G-d allow the regretting of one’s good deeds as well?
The principle of regretting one’s good deeds, whereby one loses their reward, is that the judgment of a person is based on the person himself, and not on his deeds. True, a perosn might have done a good deed, but if he regrets doing it, to the point that he wishes he would never have done it, he detaches himself, as it were, from the good deed. On the scales of justice, the good deed, as it were, loses its weight. If it is insignificant for the person that performed it, it simply has no weight.
This explanation emerges from the wording of the Rambam, in his Laws of Repentance (chap. 3), where he mentions the principle of regretting one’s good deeds as part of the ‘weighing process’ of a person’s mitzvos and aveiros.
[Originally heard from Rav Moshe Shapira.]