金剛般若經贊述 1.87

1.87

Question: "Why is it not permissible to ask how good sons, etc., should abide regarding the bodhi of the three vehicles, but only speaks of the Mahāyāna? As the Śrīmālādevī Sūtra states: 'Those who shoulder the four heavy burdens gather in and benefit both those with the lineage (gotra) and those without the lineage.'" Answer: "The commentary explains it in terms of the meaning of 'non-apprehendability'. That is, since Subhūti is a śrāvaka, for him to ask about the abiding and practice of the Mahāyāna is something exceptional and rare (lit. 'unobtainable'); if he asked about the abiding and practice of the two vehicles, it would not be a difficult thing, and the Bhagavat would not have praised him with 'Excellent!'. Furthermore, he inquired well for the sake of distinguishing the three kinds of bodhi, and therefore solely asked about the arousal and practice of the Bodhisattvayāna."