妙法蓮華經玄義 6.132

6.132

伽陀者，如龍女獻珠，喜見說偈，孤然特起。此偈明於剎那頃便成正覺，稱歎於佛成菩提事。喜見孤起，歎佛容顏甚奇妙，故知孤起伽陀妙也。

As for gāthā (isolated verses): such as the dragon girl presenting the jewel, or Priyadarśana speaking verses, which arise isolated and distinct. These verses clarify that in a single instant she attained right enlightenment, praising the Buddha's attainment of bodhi. Priyadarśana's isolated verse praised the Buddha's countenance as extraordinarily wonderful; hence we know that the isolated gāthās are subtle.