成唯識論述記 3.220

3.220

述曰：下引教成，《佛地論》有，即《厚嚴經》。謂即內、外二性，此內外一切分，皆有所取、能取纏繞，故有四分。

The Commentary states: Below, it cites scripture for confirmation. It is found in the Buddhabhūmi-śāstra, namely the Ghanavyūha-sūtra. That is, the two natures of internal and external: all these internal and external parts are entwined with the grasped and the grasper; hence there are four parts.