金光明經文句記 2.185

2.185

初、明報佛體圓。上約品題壽量二字不偏有無，則收二應能顯法報，就文便也。若義便者，今經既以果德為宗，合以報身釋於品目，以報身上冥下應，則三身義任運成就，是故二字正在報身。

First, it explains that the substance of the reward Buddha is perfect. Above, treating the two characters of the chapter title, "span of life," as not leaning toward either existence or nonexistence encompassed the two responsive [bodies] and was able to reveal the Dharma and reward [bodies], which was convenient according to the text. If one considers what is convenient in terms of the meaning, since this sūtra takes the fruit virtue as its principal theme, it is fitting to explain the chapter title by means of the reward body; because the reward body unites obscurely above and responds below, the meaning of the three bodies is spontaneously established. Therefore, the two characters refer precisely to the reward body.