俱舍論記 22.167

22.167

「既立不淨名唯不淨行相」者，釋頌不淨。又《正理》云「此觀行相唯不淨轉，是善性故體應是淨，約行相故說為不淨。」又《婆沙》云「行相者，非十六行相。」

The words 'Since it establishes the name "impure", its mode of activity is only impure' explain 'impure' in the verse. Furthermore, the Nyāyānusāra says: 'The mode of activity of this contemplation proceeds only as impure; since it is wholesome in nature, its essence ought to be pure, but with respect to its mode of activity it is spoken of as impure.' Furthermore, the Mahāvibhāṣā says: 'Regarding "mode of activity", it is not the sixteen modes of activity.'