成唯識論述記 9.119

9.119

述曰：第四難也。有漏習氣是識相分，相分既非有，豈體非有之法能作因緣？假法如無，非因緣故。汝執相分體非有故，彼執種子非真有體，自證分緣仍非相分，今說自宗言「相分攝」，故為此難。

The Commentary states: The fourth objection. Sāsrava vāsanās are the nimitta-bhāga of consciousness; since the nimitta-bhāga does not exist, how could a dharma whose substance does not exist be able to act as a cause and condition? Conventional dharmas are like non-existence, and are not causes and conditions. Because you grasp that the nimitta-bhāga lacks substance, he grasps that seeds do not truly have substance, and what the self-verifying part cognizes is still not a nimitta-bhāga; now stating our own school's position that they are 'subsumed under the nimitta-bhāga', this objection is made.