成唯識論述記 4.270

4.270

述曰：則同外道。外道邪見毀謗，亦不謂染、淨等皆無，現所見故，但執非實。染因不能感惡果，善因不能感善果，以非實故，如空華等。

The Commentary states: Then they are identical to non-Buddhists. The wrong views and disparagements of non-Buddhists also do not mean that defilement, purification, and so forth are entirely non-existent, because they are visibly seen; they merely cling to them as unreal: defiled causes cannot bring about bad fruits, and wholesome causes cannot bring about wholesome fruits, because they are unreal, like sky-flowers and the like.