首楞嚴義疏注經 1.160

1.160

認他虛想也。下文云「此是前塵虛妄相想，惑汝真性，從無始來認賊為子，失汝元常，故受輪轉。」舉世修行多同此計，故託阿難總彰其失。

This is mistaking alien, unreal thoughts [for oneself]. A later passage says: 'These are the unreal, deluded conceptualized characteristics of preceding sense-objects, which delude your true nature. From beginningless time, you have mistaken a thief for your child, losing your original permanence, and therefore suffer transmigration.' Most practitioners in the world share this reckoning; therefore, relying on Ānanda, [the Buddha] reveals their fault in general.