Will he do so only on the seventh?
Rashi: It means, so you will do all seven days. So it says above "Shiv'as Yamim Yechaperu Es ha'Mizbe'ach" (43:26).
Rashi citing Menachos 45a: "V'Chen Ta'aseh" ? and so you will bring a bull that is not eaten (Par Helam Davar), "ba'Shivah" - for seven Shevatim 1 that sinned "va'Chodesh" via a Chidush, i.e. the Great Sanhedrin mistakenly changed the Halachah and permitted Chelev (or a similar Isur Kares). "Me'Ish Shogeh umi'Pesi" - the Korban is brought only if the Hora'ah was mistaken and the people sinned b'Shogeg.
Radak, Malbim: Yes. Radak - this will be a Chidush in the future, to purify the Mizbe'ach and Bayis also on the seventh of the month. Due to great Simchah of Chanukas ha'Mizbe'ach, perhaps someone entered b'Shogeg in a place where he may not enter, and due to this they will atone also on the seventh.
45a: They are the majority of Shevatim, even if they are they are the minority of Yisrael.
What do we learn from "me'Ish Shogeh umi'Pesi [v'Chipartem Es ha'Bayis]"?
Rashi: The verse should be re-arranged. V'Chipartem Es ha'Bayis me'Ish Shogeh umi'Pesi ? after the seven days of the Milu'im, the Mizbe'ach is inaugurated, people will bring their Chata'os and Ashamos and get Kaparah. When Yisrael have Kaparah, the Bayis has Kaparah.
Radak 1 : This teaches that they bring [Par Helam Davar] only for a mistaken ruling and Shigegas Ma'aseh (most of Yisrael sinned due to it).
Malbim: This refers to "v'Chiteisa Es ha'Mikdash" (18). The Chiuty on Rosh Chodesh is to atone for Mezid. The Chiuty on the seventh is to purify from Shegagah, i.e. what one sinned via mistaken investigation, e.g. he ruled incorrectly, or via Patiyus (folly). These bulls are to atone for the Bayis; the bulls and goats offered from Zayin Adar 2 until Rosh Chodesh Nisan, like it says above (45:27) were to atone for the Mizbe'ach.
Refer to 45:22:1:1*.
Either this means 'the last seven days of Adar', or the text should say 'the 23rd of Adar.' (PF)
