The latter Musar sages were divided about one who repeated a sin several times. Some contend that he must fast the number of fasts appropriate to that sin according to the number of transgressions. For example, the number of fasts prescribed in the penances of the Ari for wasteful emission of semen is eighty-four. If someone commits this sin ten or twenty times, say, he must fast ten or twenty times eighty-four, and so on in all instances. These sages compare the fasts to thechatat offering required for every instance of violation.
Others compare fasts to the olah offering brought for neglect of a positive command. Violation of a number of positive commands is atoned for by one olah, as the Talmud explains in Zevachim, ch. I.
The accepted decision in this dispute is to fast three times the number of fasts prescribed for that specific sin, i.e. 252 for emission, and similarly for other sins. This is based on an observation in Zohar, end of Noach; as soon as mortal man is guilty one time before the Holy One, blessed be He, he makes an impression ... the third time the stain penetrates from one side through the other... Therefore the number of fasts ought also be three ...
However, all this applies to the strong and healthy, whose physical vigour would not be sapped at all by repeated fasts, as in the generations of yore. But whoever would be affected by many fasts, and might suffer illness or pain, G-d forbid, as in contemporary generations, is forbidden to engage in many fasts. This ban concerns even sins of excision or execution, and certainly the positive and prohibitory commands that do not involve excision. Instead the measure of fasting is the personal estimate of what he can tolerate without doubt.
For even in those early Talmudic generations, only the robust who could
mortify themselves fasted so frequently. But whoever cannot fast and does, is called "sinner" in Taanit, ch. I. This applies even to one who fasts for specifically known sins, as Rashi explains there, and we find inZevachim, ch. I, that there is no one of Israel who is not guilty of a positive commandment ...
It goes without saying that a student of Torah who fasts, sins and is doubly punished, for the weakness resulting from his fast prevents him from studying Torah properly.
What then is his alternative ? "Your sin redeem with charity." The codifiers of Torah law specified for each fast day of repentance approximately eighteen (coins) .. . The wealthy shall add according to his means ... See Magen Avraham on laws of Fasts.
Nonetheless, every man of spirit who desires to be close to G-d, to repair his soul, to return it to G-d with the finest and most preferred repentance, shall be stringent with himself. He should complete, at least once during his life span, the number of fasts for every grave sin incurring death at least, if only death by divine agency. For example, for wasteful emission he should undergo the series of eighty-four fasts once in his life. He may postpone the fasts until the shorter winter days and fast some ten days or less, for example, in one winter, and complete the series of eighty-four in nine or more years according to his stamina. (Besides, he may also eat a little about three hours before sunrise, and this would still be considered a fa'st, if he so stipulated.)
For the completion of the mentioned 252, he may fast another four rimes eighty-four until past noon, which the Talmud Yerushalmi considers a fast. In this context, two half-days are reckoned as one full day. Naturally, this approach applies to any other sins, for each heart knows its own anguish and desires its vindication.
There still remain the fasts in excess of the 252, or whatever amount, that he ought to fast in deference to the more stringent opinion insisting on the appropriate number of fasts for every violation committed, as noted. These may be redeemed with charity, approximating eighteen (coins) for each fast day. Charity may redeem all other fasts that he should have undergone for sins not entailing death, and even for neglecting a positive command, Torah or Rabbinic, and neglect of "Torah study which equals them all," aaxurding to the number of fasts prescribed by the Ari's penances. (Most of these are noted in Mishnat Chassidim, Tractate Teshuvah.) All of these fasts he may redeem with charity if he cannot mortify himself, as noted.
Though this might amount to a considerable sum, he need not fear for the injunction, "Do not distribute more than one fifth." These circumstances are not "distribution" for charity, since he does this to release himself from fasting and affliction. This is no less necessary than medicine for his body or his other needs.
The number of fasts enumerated in the above-mentioned penances is exceedingly great. Therefore all who revere the word of G-d are now accustomed to being unstintingly generous with charity, for the prevalent lack of hardihood prevents them from mortifying themselves over much. (A comment is made elsewhere on this subject on the verse, "The kindnesses of G-d, for they are not concluded.")