成唯識論了義燈 2.40

2.40

疏云：此但應言，如二極微，量以三微果等，因非極微故。此意以第三子微，果量等於因，然是麁色，不是極微。

The Commentary states: 'Here one should merely say: just as two paramāṇus measure equal to the effect of three aṇus, because the cause is not a paramāṇu.' The meaning here is that the measure of the effect of the third secondary atom is equal to the cause, yet it is coarse form and not a paramāṇu.