Mishnayos Shevuos Perek 1 Mishnah 1

With regard to oaths on an utterance of the lips, there are two types that are actually four types. The Torah specifies only two types of oaths whose violation renders one liable to bring a sliding-scale offering to atone for his transgression (see Leviticus 5:4): Where a person takes an oath to perform some action, and where he takes an oath to refrain from performing some action. With regard to both types, the Torah explicitly mentions liability only for an oath pertaining to one’s future behavior. Nevertheless, the Sages derive that one is also liable for a violation of both types of oaths when they pertain to one’s past behavior. Accordingly, although only two types are explicitly mentioned in the Torah, the Sages derive that there are actually four types. The mishna lists similar groups of halakhot. With regard to cases of awareness of the defiling of the Temple by entering it while one is ritually impure, or defiling its sacrificial foods by partaking of them while one is ritually impure, there are two types that are actually four. It is prohibited for an impure person to enter the Temple (see Numbers 19:20) or to partake of its sacrificial foods (see Leviticus 7:19–20). If one transgressed either prohibition during a lapse of awareness, then upon becoming aware of his transgression, he is liable to bring a sliding-scale offering (see Leviticus 5:2). The Torah specifies that one is liable to bring the offering only in the case in which he had a lapse of awareness of the fact that he was impure. The Sages derive that one is liable not only in these two cases, but also where he was aware of his personal status but had a lapse of awareness concerning the identity of the place he was entering or the status of the foods he ate. With regard to acts of carrying out that are prohibited on Shabbat, there are two types that are actually four. On Shabbat, it is prohibited to transfer an item from domain to domain. The Torah explicitly refers to only two cases, both of which involve an item being transferred from a private domain to a public domain: Where the transfer is made by a person who remains in the public domain, and where the transfer is made by a person who remains in the private domain. The Sages derive that liability is incurred in these cases also if the item is transferred from the public domain to the private domain. Although only two types are mentioned by the Torah, the Sages derive that there are actually four types. With regard to shades of leprous marks on a person’s skin, there are two types that are actually four. The Torah specifies that if a leprous mark appears on a person’s skin, the afflicted person must undergo a process of purification and then bring various offerings. Part of the classification of these types of leprosy is based on their shade of white. Two types of marks are explicitly mentioned in the Torah, and the Sages derive that each of these two types has a secondary mark.

שְׁבוּעוֹת שְׁתַּיִם שֶׁהֵן אַרְבַּע, יְדִיעוֹת הַטֻּמְאָה שְׁתַּיִם שֶׁהֵן אַרְבַּע, יְצִיאוֹת הַשַּׁבָּת שְׁתַּיִם שֶׁהֵן אַרְבַּע, מַרְאוֹת נְגָעִים שְׁנַיִם שֶׁהֵם אַרְבָּעָה: