Moed Katan 26B

ובאיחוי אלכסנדרי.

And the reference here is to the Alexandrian method of mending, a type of sewing performed in Alexandria, which is considered to be of exceptional quality and after which the tear is no longer visible.

תנו רבנן: הקורע מתוך השלל מתוך המלל מתוך הלקט, מתוך הסולמות ⁠— לא יצא. מתוך האיחוי ⁠— יצא. אמר רב חסדא: ובאיחוי אלכסנדרי.

A baraita states the following baraita: One who rends his garment in a place that had been loosely tacked together, or from the hem of the garment, or on the gathering, or on the ladder-like stiches has not fulfilled his obligation to rend it. But if he rends it in a place that had been carefully mended, he has fulfilled his obligation, because such a garment is regarded as whole. Rav Ḥisda said: And here, too, the reference is to the Alexandrian method of mending and not to ordinary sewing.

תנו רבנן: רשאי להופכו למטה ולאחותו. רבי שמעון בן אלעזר אוסר לאחותו, וכשם שהמוכר אסור לאחותו ⁠— כך הלוקח אסור לאחותו. ולפיכך מוכר צריך להודיעו ללוקח.

A baraita states another baraita: One is permitted to turn a garment that was rent on the upper edge upside down and then mend it in a precise fashion. R' Shimon ben Elazar prohibits careful mending in this case as well. And if one wishes to sell a garment that he had previously rent in mourning, just as the seller, who had rent the garment, is prohibited from carefully mending the garment, so too the buyer, who purchases it from him, is prohibited from mending it. The seller must therefore inform the buyer that the rent was made on account of mourning and may not be mended.

תנו רבנן: תחילת קריעה ⁠— טפח, ותוספת ⁠— שלש אצבעות, דברי רבי מאיר. רבי יהודה אומר: תחילת קריעה ⁠— שלש אצבעות, ותוספת ⁠— כל שהו.

A baraita states a baraita: The initial rending is a handbreadth in length, and the extension, if one is obligated to rend his garment for other deceased relatives and he wishes to use the same rent for this purpose, is 3 fingerbreadths; this is the statement of R' Meir. R' Yehuda says: The initial rending is 3 fingerbreadths in length, and its extension is any amount, with no minimum measure.