成唯識論述記 8.177

8.177

述曰：謂要能緣種心、心所法，種子方為彼所緣緣，除一切相分，相分不能緣故，及除自體分，不緣種故。然見分中，除五、七識不緣種故，但與第八一切時見分、第六有時緣者，彼與為緣。今簡爾所不為緣故，言為所緣於能緣者，是簡略言。

The Commentary states: This means that there must be mind and mental factor dharmas capable of cognizing the seeds before the seeds can serve as their objective condition, excluding all nimittabhāgas, because nimittabhāgas cannot cognize, and excluding the self-substance part (svabhāgabhāga), because it does not cognize seeds. Furthermore, within the darśanabhāga, the fifth and seventh consciousnesses are excluded because they do not cognize seeds; it serves as a condition only for the darśanabhāga of the eighth [consciousness] at all times, and for the sixth [consciousness] when it cognizes them at times. Now, to exclude all those for which it does not serve as a condition, it says 'serves as the objective condition for that which is capable of cognizing'; this is a concise statement.