金光明最勝王經疏 2.16

2.16

問：四佛如來妙幢室說，爾時慶喜在鷲峯山，如何結集云我聞等？答：準下文云「妙幢菩薩與無量大眾詣鷲峯山頂禮佛足，以如上事具白世尊。」是故得云我聞如是。

Question: The four Tathāgata Buddhas spoke in Ruciraketu's chamber; at that time, Ānanda was on Gṛdhrakūṭa Mountain; how could the compiler say 'Thus have I heard' and so on? Answer: In accordance with the text below, it says: 'Bodhisattva Ruciraketu, along with an immeasurable great assembly, went to Gṛdhrakūṭa Mountain, bowed at the Buddha's feet, and reported the matters above in full to the World-Honoured One.' Therefore, one can say 'Thus have I heard'.