If orphans of a creditor wish to collect their debt from the orphans of the borrower on the basis of a note recording the loan, they must take an oath that their father never told them that the loan was paid and that they found nothing amongst their fatherrecords indicating that it had been paid. Regarding this ruling of the mishna, Rabbi Zerika cited the qualification made by Rabbi Yehuda: The need for such an oath only arises when the borrower's heirs claim that their father already paid; should they claim, however, that he never borrowed, the creditor's heirs can collect without an oath.

This is so, explains the gemara, because anyone who claims he never borrowed is essentially admitting that he never paid. Since the debtor's heirs' claim of never having borrowed is refuted by the debt note presented by the creditor's heirs, it is now considered as if they have admitted non-payment, and there is no longer a need for the oath.

A person's admission of debt is sufficient to obligate him. Although regarding issues of corporal or capital punishment a person is not believed to incriminate himself, in respect to monetary obligations the rule is that "a person is believed regarding himself more than a hundred witnesses."

An interesting application of how he is believed more than witnesses is provided by the Sage Rava (Mesechta Shavuot 41b) in the case of a man who denied ever having borrowed from the creditor making a claim against him. Witnesses came to testify that he had indeed borrowed but had repaid the loan. Rava ruled that the borrower must pay, since his claim of never having borrowed is equivalent to an admission of non-payment, and this admission has more power than the testimony of witnesses who say that he did pay.

This gemara is cited by Rabbi Aryeh Leib Hakohen (Ketzot Hachoshen 34:4) as a challenge to the approach of the Mahari Even Lev in explaining why a person is believed to obligate himself although he is considered a relative to himself and therefore disqualified as a witness. His explanation is that we do not actually believe his self-incriminating testimony, but rather view his admission as a self-imposed obligation to make a gift to the claimant. This might apply, argues the Ketzot, when one actually admits owing something. But when one claims that he never borrowed, he shows no indication of an interest in making a gift. His own conclusion is that there is a special Torah law requiring us to believe a person's self-incriminating testimony in monetary matters even more than that of many witnesses.

One side of a major halachic debate on the issue of pre-teen marriage receives an indirect support from the final mishna of the ninth perek of Ketubot.

The debate is over whether it is proper for a father to marry off his son before he is of Bar Mitzvah age. It revolves around a gemara (Mesechta Sanhedrin 76b) which recommends marrying off sons and daughters "close to their period of adulthood." While we are well aware that the Torah empowered a father to marry off his daughter at even the youngest age, he has no such power regarding his son. Rambam therefore concludes that the age referred to here is above the age of Bar Mitzvah, age 13. Below that age, he writes, such a marriage is considered the equivalent of promiscuity.

Rashi and Tosefot, however, both define the period mentioned in the gemara as before the age of Bar Mitzvah (Rashi writes a half-year or year before). One of the supports Tosefot cites for his view is a mishna which discusses the status of a ketubah which was written for the marriage of a boy before Bar Mitzvah age. Whether Tosefot's intention was to sanction the marriage of a boy only within the year preceding Bar Mitzvah or even earlier is a matter of debate between the later halachic authorities, with some contending that, while the mitzvah mentioned in Mesechta Sanhedrin is limited only to that last year of childhood, the right to marry off a boy so that it not be considered promiscuity applies to an even earlier age.

It should also be pointed out that no mention is made in halachic literature as to the frequency of pre-teen marriages for boys. In regard to girls, however, Tosefot (Mesechta Kiddushin 41a) notes that even though the gemara discourages a father from exercising his right to marry off his daughter until she reaches adulthood (Bat Mitzvah) and is mature enough to give her consent, it was customary in their days to arrange such childhood marriages. The reason was that the perilous economic situation of Jews in exile made it urgent to marry off a daughter when the father could afford a dowry, and not to postpone an opportunity that might not recur.