俱舍論記 3.56

3.56

「先依無漏至說此言故」者，釋。以契經中先依無漏信等五根建立四果、四向諸聖位差別已。說此言故，若全無此無漏信等五根，我說彼住外異生品，非攝有漏。

Regarding "Having first based on the untainted […] spoken with this meaning": this is the explanation. In the sūtra, having first established the distinctions among the various noble stages of the four fruits and the four approaches based on the untainted five faculties of faith and the rest, it then spoke these words: 'If one entirely lacks these untainted five faculties of faith and the rest, I say that they abide in the category of external ordinary persons'—it does not subsume the tainted ones.