瑜伽論記 4.307

4.307

言若無無我，無常苦觀，終不清淨者，此反釋也。若無真見道中無我空定，相見道中，無常苦觀，終不清淨。言要先安立無我之想，從此無間方得無願者，此順釋也。要先於真見道安住無我，從此無間入相見道方得無願。

The statement "if there were no non-self, the contemplation of impermanence and suffering would never be purified" is a reverse explanation: if there were no non-self emptiness samādhi in the true path of seeing, the contemplation of impermanence and suffering in the path of seeing with signs would never be purified. The statement "one must first establish the conception of non-self, and immediately following this one attains wishlessness" is a forward explanation: one must first abide in non-self in the true path of seeing, and immediately following this enter the path of seeing with signs to attain wishlessness.