金光明經文句記 6.170

6.170

三、「希有」下一行半，就垂世形益讚佛應身。優曇花者，具足云優曇鉢羅，此言瑞應，亦云靈瑞，輪王出世時感此華。《泥洹經》云「閻浮提內有尊樹王，名優曇鉢羅，有實無華。」優曇鉢樹有金華者，世乃有佛，故云時一現耳。無量大悲者，垂應本也。以大悲故，不住涅槃。

Third, the line and a half from "Rare..." downward praises the Buddha's response body in terms of the forms and benefits manifested in the world. As for the udumbara flower, fully stated it is called "udumbara"; here it means an auspicious response, or also a marvelous portent, which is induced when a wheel-turning king appears in the world. The Nirvāṇa Sūtra says: "In Jambudvīpa there is an exalted tree-king named udumbara, which bears fruit but no flowers." When the udumbara tree bears golden flowers, only then does a Buddha exist in the world; hence it is said, "It appears only once in a while." "Immeasurable great compassion" is the source of manifesting the response [body]. Because of great compassion, he does not abide in nirvāṇa.