俱舍論記 6.23

6.23

「如是諸相至亦更互為因」者，問。何故不說諸相及隨轉各互為因？答：《正理》云「為欲顯示但說異類為俱有因，同類互為因不說而成故。」

Regarding '[Thus the primary characteristics ... are also mutually causes]', this asks: Why is it not stated that the primary characteristics and the conforming [dharmas] are mutually causes among themselves? Answer: Nyāyānusāra says: 'In order to demonstrate this, it only speaks of different categories as coexistence causes, because that homogeneous ones are mutually causes is established without being stated.'