大般涅槃經集解 9.18

9.18

案僧亮曰：此先譬說、後法說也。菩薩有外行內行。慈是外行之因，八河歸海，外行果也；群生是內行因，涅槃佛性，是內行果也。次說三寶一體，重顯二果常也。王自迴駕者，獄為不淨，非王行處，慈故至也。五道是苦，非菩薩所居，亦以慈故，難至而能至也。

Sengliang comments: This first speaks through a simile and later speaks of the Dharma. Bodhisattvas possess both external practices and internal practices. Benevolence is the cause of external practice; just as the eight rivers return to the sea, such is the fruition of external practice. Sentient beings are the cause of internal practice; nirvāṇa and buddhadhātu are the fruitions of internal practice. Next, it speaks of the Three Jewels as one single body, further clarifying that the two fruitions are permanent (nitya). Regarding the king personally turning his carriage: the prison is an impure place and not somewhere a king travels, yet he goes there out of benevolence. The five destinies are suffering and not places where a bodhisattva dwells, yet also out of benevolence, though difficult to reach, he is able to reach them.