大般涅槃經集解 2.61

2.61

案僧宗曰：為三明六通作譬也。龍有二德：一則興雲降雨、二則隱顯自在也。寶亮曰：此下訖逮得己利，辨應供也。道慧記曰：龍王即是人中象王。如《大品經》云「如調象王」也。為善調作譬，釋煩惱所以而離，由乎善調諸根故也。

Sengzong states: This serves as a metaphor for the three knowledges and six supernormal knowledges. Dragons have two virtues: first, raising clouds and sending down rain; second, concealing and revealing themselves at will.
Baoliang states: From here down to "having attained their own benefit", it distinguishes "worthy of offerings".
Daohui's Notes state: Dragon-kings are elephant-kings among humans, as the Pañcaviṃśatisāhasrikā Prajñāpāramitā Sūtra says: "like well-tamed elephant-kings". It serves as a metaphor for being well-tamed, explaining that the reason afflictions are shed is due to well-subduing the faculties.