MISHNA: Samaritan girls are considered menstruating women from the time they lie in their cradle. And the Samaritan men impart ritual impurity to the lower bedding like the upper bedding, i.e., all layers of bedding beneath them are impure, and their status is like the bedding above a man who experiences a gonorrhea-like discharge [zav]: The status of both levels of bedding is that of first-degree ritual impurity, which can impart impurity to food and drink. This is due to the fact that Samaritan men are considered men who engage in intercourse with menstruating women. מתני׳ בנות כותים נדות מעריסתן והכותים מטמאים משכב תחתון כעליון מפני שהן בועלי נדות
And they are considered men who engage in intercourse with menstruating women because Samaritan women observe the seven-day menstrual period of ritual impurity for each and every emission of blood, even for blood that does not render them impure. Accordingly, if a Samaritan woman has an emission of impure blood during the seven-day period, she will nevertheless continue counting seven days from the first emission. It is therefore possible that the Samaritan men will engage in intercourse with their wives while they are still halakhically considered menstruating women, as the seven-day period of impurity should have been counted from the emission of the impure blood. והן יושבות על כל דם ודם
But one who enters the Temple while wearing those garments upon which a Samaritan had lain is not liable to bring an offering for entering the Temple in a status of impurity, nor does one burn teruma that came into contact with those garments, because their impurity is uncertain. ואין חייבין עליהן על ביאת מקדש ואין שורפין עליהם את התרומה מפני שטומאתן ספק
GEMARA: The mishna teaches that Samaritan girls are considered menstruating women from the time they lie in their cradle. The Gemara asks: What are the circumstances of this statement? If the mishna is referring to girls who already see menstrual blood, then even our own, i.e., Jewish girls, are also considered menstruating women under such circumstances. And if it is referring to girls who do not yet see menstrual blood, then their girls, i.e., those of the Samaritans, should also not have the status of menstruating women. גמ׳ ה"ד אי דקא חזיין אפילו דידן נמי ואי דלא קחזיין דידהו נמי לא
Rava, son of Rav Aḥa bar Rav Huna, says that Rav Sheshet says: Here we are dealing with an unspecified case, i.e., it is unknown whether these girls have experienced their first menstrual period. Since there is a minority of girls who see menstrual blood, we are concerned with regard to each Samaritan girl that she might be from this minority. The Gemara asks: And who is the tanna who taught that one must be concerned for the minority? אמר רבא בריה דרב אחא בר רב הונא אמר רב ששת הכא במאי עסקינן בסתמא דכיון דאיכא מיעוטא דחזיין חיישינן ומאן תנא דחייש למיעוטא