俱舍論記 10.220

10.220

「謂契經言至是名正性」者，答。此解正性。斷貪、瞋、癡及慢、疑等一切惑盡，名曰無餘。此斷即是涅槃擇滅，名為正性。

Regarding "That is, the sūtra says: ... this is called correct nature": this is the answer. This explains correct nature. The complete cutting off of greed, hatred, delusion, as well as pride, doubt, and all other defilements is called "without remainder". This cessation is precisely the analytical cessation of nirvāṇa, and is called "correct nature".