Keritot 12B

בטומאה ישנה, מאי שנא חלבין וביאת מקדש דמודו ליה, דאם רצה יאמר: ״מזיד הייתי״? טומאה ישנה נמי מתרץ דיבוריה, דאם רצה יאמר: ״לא עמדתי בטומאתי אלא טבלתי״!

that the baraita is referring to a case of old impurity, where the witnesses said to him: You became impure yesterday, what is different about the cases of eating forbidden fat and entering the Temple while impure, where the Rabbis concede to R' Yehuda that one is not liable to bring a sin offering even though his denial is contradicted by two witnesses? He is exempt since if he wished, he could say: I did so intentionally. Therefore, his denial can be interpreted to mean: My eating the forbidden fat or entering the Temple was not unwitting but intentional. If so, if he denies that he is in a state of old impurity, he can also explain his statement, since if he wished, he could say that he meant: I did not remain in my state of ritual impurity, but rather I immersed in a mikveh.

אמר רבינא: לעולם בטומאה ישנה, וכגון דאמרי ליה עדים: אכלת קדשים בטומאת הגוף, והוא אמר להון: ״לא נטמאתי״, דהכא לא מתריץ דיבוריה. דליכא למימר לא עמדתי בטומאה אבל טבלתי,

Ravina said: Actually, the baraita can be referring to a case of old impurity, and nevertheless the Rabbis distinguish between one’s denial that he is impure and one’s denial that he ate or entered the Temple. The case is one where the witnesses say to him: You ate sacrificial meat while in a state of physical impurity, and he says to them: I did not become impure. The reason he is liable to bring an offering is that here he cannot explain his statement, as one cannot say that the phrase: I did not become impure, can be explained to mean: I did not remain in a state of impurity but rather I immersed.