觀無量壽佛經疏 2.41

2.41

In saying 'the World-Honoured One also dispatched Pūrṇa to expound the Dharma for the king,' this clarifies that the World-Honoured One's compassionate intent was profound; he took pity on the king's person suddenly encountering imprisonment and feared that he would give rise to distress and exhaustion. Pūrṇa was the foremost among the sacred disciples in expounding the Dharma, skillful in expedient means to open the human mind. For this reason, the Tathāgata dispatched him to expound the Dharma for the king in order to eliminate distress and affliction.