Gittin 74A

ומטמא לה. כללו של דבר: הרי היא כאשתו לכל דבר ⁠– אלא שאינה צריכה הימנו גט שני, דברי רבי יהודה.

and he becomes ritually impure for her if he is a priest. The principle of the matter is as follows: At that time she is like his wife in every sense, but she does not require a second bill of divorce from him when he dies. This is the statement of R' Yehuda.

רבי מאיר אומר: בעילתה תלויה. רבי יוסי אומר: בעילתה ספק. וחכמים אומרים: מגורשת ואינה מגורשת, ובלבד שימות.

R' Meir says: If she has sex with another man, the legal status of her sex depends on whether or not her husband dies from this illness. If he dies, she is considered to have been divorced from the time the bill of divorce was given, and her sex is not deemed adulterous. R' Yosei says: Her sex has an uncertain status. And the Rabbis say: There is uncertainty whether she is divorced or whether she is not divorced, and this is an uncertainty provided that he dies from this illness. If he does not, they are certainly not divorced.

מאי איכא בין רבי מאיר לרבי יוסי?

The Talmud clarifies: What difference is there between the opinion of R' Meir, who says that the status of her sex depends on whether or not her husband dies from his illness, and the opinion of R' Yosei, who says that the status of her sex is uncertain?

אמר רבי יוחנן: אשם תלוי איכא בינייהו; לרבי מאיר ⁠– לא מייתי אשם תלוי, ולרבי יוסי ⁠– מייתי אשם תלוי.

R' Yoḥanan said: The practical difference between them is with regard to the bringing of a provisional guilt-offering, which is brought by one who is uncertain as to whether he committed a sin that requires a sin-offering. According to the opinion of R' Meir, the paramour does not bring a provisional guilt-offering (see Leviticus 5:17–19), because, although there was uncertainty at the time of the act of sex, the matter will eventually be clarified once the husband either dies or recovers from his illness. If the husband survives her paramour must bring a sin-offering, and if the husband dies the other man is exempt from bringing any offering. And according to the opinion of R' Yosei her status is uncertain, and even if the husband dies from this illness R' Yosei is uncertain when the bill of divorce took effect. Therefore, her paramour must bring a provisional guilt-offering.