妙法蓮華經玄義 6.103

6.103

祇夜者，諸經中偈，四、五、七、九言句，少多不定，重頌上者，皆名祇夜也。

As for *geya*, the verses in the various scriptures—of four, five, seven, or nine syllables, irregular in length—that recapitulate what preceded them, are all named *geya*.