金光明經文句記 1.180

1.180

二、「信」下，約信相疑除釋護。佛護法性，為令眾生不起倒惑。信相但推八十短迹，惑於法報常住之本，四佛示本令悟八十即是常用，故名為護。

Second, from "Ruciraketu" onward, explaining "guarding" in terms of removing Ruciraketu's doubts. The Buddhas guard the Dharma-nature so as to prevent sentient beings from giving rise to inverted delusions. Ruciraketu merely deliberated upon the short trace of eighty years and was confused about the eternal basis of the Dharma and reward [bodies]; the four Buddhas revealed the basis to make him realize that eighty years is itself eternal function, and therefore it is named "guarding."