Ben Beseira explained, [they separated him] lest he have Bi'ah with his wife when she is Nidah, and he will be [Bo'el Nidah, and] rejected from the Avodah for seven days [he cannot become Tahor until then].

Objection: Are Yisrael suspected of [Bi'ah with] Nidos?!

Answer: [The concern] is like a Mishnah teaches. If one was having Bi'ah with a Tehorah, and she told him "I became Temei'ah (Nidah)'', if he separated immediately (when the Ever is still in Kishuy), he is liable, for his separating (amidst Kishuy) is pleasurable, just like his entrance [of the Ever].

Remark: R. Yochanan's words [that we learn separation from Ka'asher Asah ba'Yom ha'Zeh...] needs [also] Ben Beseira's reason, and Ben Beseira's reason needs [also] R. Yochanan's words;

If we had [only] R. Yochanan's words, and Ben Beseira did not say [his reason], we would have said that he can had Bi'ah and sleep in Lishkas Palhedrin. Therefore, we need what Ben Beseira said;

If we had [only] Ben Beseira words, and not R. Yochanan's [his reason], we would have said that he can refrain from Bi'ah and sleep in his house. Therefore, we need what R. Yochanan said and what Ben Beseira said.

(Beraisa): All the chambers that were in the Mikdash were exempt from Mezuzah, except for Lishkas Palhedrin, which is residence for the Kohen Gadol seven days during the year;

R. Yehudah says, even this was only a decree (mid'Oraisa it is exempt, for it is forced residence. Mid'Rabanan it is obligated, lest it seem that he is in jail.)