• When a partner is believed to say he contributed toward the wall

The next Mishnah states: כותל חצר שנפל – if a courtyard wall between neighbors fell, מחייבין אותו לבנותו עד ארבע אמות – we obligate [each one] to build it up to a height of four amos, which is sufficient to block them from seeing into the other’s chatzeir. בחזקת שנתן עד שיביא ראיה שלא נתן – After it is built, each neighbor is presumed to have contributed to the wall until [the other] brings proof that he did not contribute. Since it is well known that each must contribute, we assume that neither would have built it alone. The Mishnah continues that we do not force him to contribute toward a height above four amos, even if the original wall was taller, since it is not necessary for privacy. If one neighbor did add to the height on his own, then the other neighbor built another wall nearby to build a roof across both walls, we obligate him to contribute to the additional height of the first. However, since this obligation is not so well known, he is presumed not to have paid for it until he proves that he did.

• Machlokes if people pay debts before they are due

Reish Lakish says: הקובע זמן לחבירו – If one sets a time for his friend to repay his loan, and when the due date arrives, the borrower claims he paid before it was due, he is not believed. ולואי שיפרע בזמנו – If only people would at least pay on time! The Gemara later explains that he holds: חזקה לא עביד איניש דפרע בגו זימניה – there is a presumption that a person does not pay a debt before its required time. Abaye and Rava say that a person does occasionally pay debts early, because sometimes money becomes available to him, and he says, איזיל איפרעיה – “I will go and pay him early, כי היכי דלא ליטרדן – so he will not bother me when the due date arrives.” The Gemara will conclude that the halachah follows Reish Lakish, and we rely on this חזקה even to collect from orphans without a shevuah (where the borrower died before the loan was due), even though one must ordinarily swear to collect from orphans.

מגו במקום חזקה

The Gemara asks: תבעו לאחר זמן – If he sued [the borrower] to pay him after the time it was due, and the borrower, who would have been believed to say he paid on time, instead said, פרעתיך בתוך זמני – “I paid you within my allotted time, before it was due,” is he believed? מי אמרינן במקום חזקה מה לי לשקר – Do we apply the logic of “Why should I lie,” and believe the borrower even in the face of a chazakah that people do not pay early? או דילמא במקום חזקה לא אמרינן מה לי לשקר – Or perhaps we do not apply the logic of “Why should I lie” in the face of a chazakah that people do not pay early, since his claim is not credible? The Gemara will attempt several proofs on the next Daf and deflect them, leaving the question unresolved.

Siman - Hay. The man who was believed when he said he paid his fair share in rebuilding the wall that collapsed in a shared courtyard up to four amos high using bricks made of ground hay, was not believed when he told his creditor on the due date of his loan, that he paid before the loan was due, and was told by a hay salesman passing by, that even if he made such a claim after the loan was due he would not be believed since, במקום חזקה לא אמרינן מה לי לשקר.