1) THE REQUIREMENT THAT A WITNESS BE ELIGIBLE TO TESTIFY FROM BEGINNING TO END
OPINIONS: The Gemara quotes a Beraisa that says that if a person knew testimony about a man who later became his father-in-law, he may not testify about his father-in-law while his wife is alive. Only after his wife dies may he testify about his former father-in-law. Even though, normally, a person is not permitted to testify about his father-in-law, the Gemara explains that as long as the witness was not related to the subject of the testimony at the moment that the act was witnessed, and at the moment that the testimony is given in Beis Din ("Techilaso v'Sofo b'Kashrus"), his testimony is acceptable, even though there was a period in the interim during which his testimony would not have been valid (because he was a son-in-law of the man for whom he testifies). The Gemara teaches that this principle also applies to a person who was sane at the time that he witnessed the event, lost his sanity, and then regained his sanity, and other similar circumstances.
Does the principle of "Techilaso v'Sofo b'Kashrus" also apply to a person who becomes unfit to testify because of a criminal act that he commits? Is such a person's testimony accepted when he saw the act before he sinned and testifies after he repents, even though he was a sinner in the interim, or is this case different in some way?
(a) The SHACH (CM 34:33) says that neither of these two possibilities is correct. The Shach states that after this person repents, he may testify even about events that he saw while he was an unrepentant sinner and unfit to testify. The Shach, however, does not explain why this is so.
(b) The TUMIM (CM 34:28) strongly disagrees with the Shach's ruling. The Tumim quotes the SHULCHAN ARUCH (CM 33:15) who rules that although a person may not testify about a case in which he has some monetary interest, the requirement of "Techilaso v'Sofo b'Kashrus" does not apply in such a case. That is, even when the witness saw the event at a time when it had some financial relevance to him, he is permitted to testify about the event once it has no relevance to him. What is the reason for this exclusion? Why does "Techilaso v'Sofo b'Kashrus" not apply?
The MORDECHAI explains that when the case has relevance to the witness, this does not make the person an invalid witness with regard to the event in question. Rather, it merely prevents him from testifying about that specific event. The principle of "Techilaso v'Sofo b'Kashrus" applies only to a person who has the status of an invalid witness in general, such as a relative who can never testify in any case that involves his own relative.
According to this reasoning, when a person was a Rasha at the time that he saw the event, but he repented and now wants to testify about the event, the principle of "Techilaso v'Sofo b'Kashrus" certainly applies. While the witness was a Rasha, he was an invalid witness in general and was unfit to testify in any case.
However, the words of the Mordechai actually may support the ruling of the Shach. Before the Mordechai gives this reason for why "Techilaso v'Sofo b'Kashrus" does not apply to a witness who saw an event at a time that he had a financial interest in the event, the Mordechai first gives a different explanation for this Halachah. He says that a person who saw an event at a time when he had a monetary interest in the case is allowed to testify later, because it was in his power to make himself impartial at the time that he saw the event (he could have sold his share or dissolved his interest in the case), and he immediately would have become a valid witness for the case. Therefore, the rule of "Techilaso v'Sofo b'Kashrus" does not apply to that case. The CHESHEK SHLOMO here points out that this seems to be the source for the Shach's ruling.
The Tumim himself mentions this reason of the Mordechai, but he says that it is not the primary answer of the Mordechai. (Indeed, the Mordechai's second explanation, and not his first, is mentioned by the RAMBAN.) Moreover, the Tumim says that the Mordechai's first explanation is difficult to understand in light of the Gemara here. The Gemara states that "Techilaso v'Sofo b'Kashrus" is required in the case of the son-in-law, but in that case the son-in-law has it in his power to become a valid witness by divorcing his wife, thereby making him impartial and enabling him to testify.
The Cheshek Shlomo answers that divorcing one's wife is not comparable to selling one's monetary interests. One can buy and sell in a moment, but to write and give a Get with witnesses takes a considerable amount of time and effort. This is why a person can be considered a valid witness when it is in his power to sell his interest in the case, but he is not a valid witness when it is in his power to divorce his wife.
It seems, however, that the Shach later (CM 35:7) retracts his opinion. He writes that one may testify only about events that he saw when he was a valid witness (and not while he was a sinner), because of the requirement of "Techilaso v'Sofo b'Kashrus." (Y. MONTROSE)
2) DETERMINING THE AGE OF AN ANIMAL
QUESTION: The Gemara quotes Rav Acha bar Yakov who derives from the words "Keves Ben Shenaso" (Vayikra 12:6) that the age of an animal (with regard to bringing it as a Korban) is calculated based on the day of the year on which it was born, and not by how many Rosh Hashanah festivals have passed since its birth.
Why is it necessary to derive this rule from a verse? It seems to be obvious. Logically, if the age of an animal would be determined based on Rosh Hashanah, then it would be impossible to bring a one-year old Korban (such as a Korban Tamid) on Rosh Hashanah itself. If the animal was born at any time within a year, and up to eight days, before Rosh Hashanah, then it would not be considered to be in its first year on Rosh Hashanah, but rather it would be in its second year. If it was born on Rosh Hashanah, or less than eight days before Rosh Hashanah, then it is not valid for a Korban because it is not yet eight days old (it is "Mechusar Zeman")! (HA'RAV SHMUEL BEN HA'RAV ELCHANAN, quoted by TOSFOS here, DH Shenaso)
(a) TOSFOS answers that the verse teaches that the age of an animal is calculated by taking into account even the time of day at which the animal was born (that is, we measure its age "me'Es l'Es").
(b) REBBI AKIVA EIGER suggests that the verse is necessary for the following reason. Rebbi Elazar in Rosh Hashanah (10a)) maintains that only after one month passes do we add a year to a person's or animal's age, while Rebbi Meir asserts that after one day of a year has passed we add a year to a person's or animal's age. The question of Tosfos is valid only according to the opinion of Rebbi Meir, who maintains that an eight-day-old animal is considered to be one-year-old on Rosh Hashanah. According to Rebbi Elazar, animals born less than thirty days before Rosh Hashanah certainly may be brought on Rosh Hashanah, since they are not yet considered one-year old (since thirty days have not passed). According to Rebbi Elazar's opinion, the verse of "Ben Shenaso" is needed to teach that animals that were born more than thirty days before Rosh Hashanah are still considered to be "in their first year" even after Rosh Hashanah. (See also Insights to Bechoros 27:4.)
3) THE SOURCE FOR CALCULATING THE YEARS "ME'ES L'ES" FOR THE REDEMPTION OF A "SEDEH ACHUZAH"
OPINIONS: The Gemara infers from the verse, "According to the number of years of crops, he will sell it to you" (Vayikra 25:15), that it is possible for a field to yield three harvests in only two years. The Gemara derives from here that one must wait two years before he buys back a Sedeh Achuzah that he sold, and those years are calculated from the day of the year on which the field was sold, and not according to the number of Rosh Hashanah festivals that have passed since the sale. How exactly does the Gemara derive this from the verse?
(a) RASHI (DH Shtei Shanim, and DH Shtei Tevu'os) explains that the minimum number expressed by the word "years" is two. Since the verse mentions no specific number of years, we may assume that it refers to the minimum number of "years," which is two.
However, this still does not teach whether these years are counted from the day of the sale or whether they are based on the number of Rosh Hashanah festivals that have passed. The additional word "crops" ("Tevu'os") teaches that the buyer is permitted to eat as many crops as he can harvest in those two years. This must refer to three harvests during those two years, because -- assuming that fields yield one crop per year -- the buyer still can eat three crops if he purchases the field when it is ready for harvesting. Rashi gives the example of a buyer who purchases a field that is ready to be harvested during Nisan. He can harvest it that year in Nisan, harvest it the next Nisan, and harvest it again the following year, before two full years have passed. If the years are calculated according to how many Rosh Hashanah festivals have passed, then the two years would have been completed six months earlier, and he would not have been able to harvest a third crop within two years. This shows that the two years are calculated from the day of the sale.
(b) TOSFOS (DH b'Mispar) asks that perhaps the verse means that one must be able to eat four crops. "Years" indicates two, and "crops" indicates another two.
What exactly is Tosfos asking?
The CHOK NASAN and OLAS SHLOMO explain that Tosfos is bothered by the assertion that "years" ("Shenei") conclusively means two years. If "years" implies a minimum of two, and "Tevu'os," which is also plural, also implies a minimum of two, then the verse presumably is teaching that one can eat four crops during this time. Accordingly, the verse seems to teach that the amount of time that must pass before one may redeem a Sedeh Achuzah is three years, and not two. How, then, does the Gemara learn from the verse that the amount of time that must pass is only two years? This is the question of Tosfos.
Tosfos therefore gives a slightly different explanation for the Gemara from that of Rashi. Tosfos understands that the word "Tevu'ah" (in the singular) would have been appropriate here. This word would have taught that a person can eat two crops during these two years, and the years would have been counted from Rosh Hashanah. The fact that the Torah says "Tevu'os" (in the plural) teaches that it is possible to eat more than two crops (i.e. three crops) within these two years. This is the proof that the years are counted from the day of the sale.
(The YAD BINYAMIN has difficulty with Tosfos' question. Why would one have thought that the Torah says "Tevu'os" in order to imply three years? The reason why the Torah sometimes uses a plural form such as "years" in order to imply two years is that the minimum amount of "years" in the plural is two. However, if the Torah wanted to express three years, then it would have said explicitly "three years," instead of saying "years of crops" in order to imply three years. Why, then, would one have thought that the Torah's intention in saying "Tevu'os" is to teach that three years must pass? He leave this question unanswered.) (Y. MONTROSE)