法華經義記 2.37

2.37

所以復據八百弟子中最下者歎妙光德廣，明彌勒應問文殊者，但此八百人皆是文殊往日弟子，但彌勒親自是八百之中最下劣者，今作補處菩薩，彌勒往日復是文殊弟子，弟子問師，正得其宜也。

As for why it further bases itself on the lowest among the eight hundred disciples to praise Varaprabha's breadth of virtue and clarify that Maitreya ought to question Mañjuśrī: these eight hundred persons were all Mañjuśrī's past disciples, but Maitreya personally was the lowest and most inferior among the eight hundred; now he is a bodhisattva in the stage of succession. Since Maitreya in the past was Mañjuśrī's disciple, for the disciple to question the master is entirely fitting.