Tafsiran Imamat 16:6: Rashi, Kitzur Ba'al HaTurim, Rashbam & Siftei Chakhamim

את פרי החטאת אשר לו [AND AARON SHALL OFFER] THE BULL OF SIN OFFERING WHICH IS HIS — i. e. that mentioned above (v. 3). It teaches you here, by adding the words אשר לו, that it came (had to be purchased) from his own and not from the money of the community (Sifra, Acharei Mot, Section 2 2; Yoma 3b).

And atone. In gematriyah this equals “זה בוידוי דברים” (this is with oral confession), for his confesses on the bullock of his sin-offering.

והקריב אהרן, in the courtyard, עזרה,

וכפר בעדו ובעד ביתו means, he shall make confession over it of his own sins and of the sins of his house (Sifra, Acharei Mot, Section 2 2; Yoma 36b).