法華經義記 2.36

2.36

所以言舉八子八百弟子讚歎妙光道高德廣者，自有義。前舉八子正歎妙光道高者，明文殊應答，昔日妙光即今是文殊故也。後舉八百弟子中最劣人歎妙光德廣者，明彌勒應問，昔日最劣弟子即今是彌勒故。何以知然？大眾疑言：彌勒已補處大士正應答，文殊非補處大士故正應問；而今云何彌勒反問文殊？文殊雖然以答彌勒，時眾既有如此疑，故今者釋言：昔日日月燈明佛在俗有八子，此八子昔日是文殊弟子，文殊教化八子皆成佛道，八子之中最後成佛者名曰燃燈，燃燈佛即是定光，定光佛即是釋迦之師，釋迦復是彌勒之師，然則文殊即是釋迦祖師；若據彌勒，曾祖師也。是故文殊應答、彌勒應問也。

As for why it brings up the eight sons and eight hundred disciples to praise Varaprabha's loftiness of way and breadth of virtue, it has its own rationale. The earlier bringing up of the eight sons directly praises Varaprabha's loftiness of way to clarify that Mañjuśrī ought to reply, because Varaprabha of the past is now Mañjuśrī. The later bringing up of the most inferior person among the eight hundred disciples to praise Varaprabha's breadth of virtue clarifies that Maitreya ought to question, because the most inferior disciple of the past is now Maitreya. How is this known to be so? The great assembly had doubts, saying: "Maitreya is already a mahāsattva in the stage of succession, so he properly ought to answer; Mañjuśrī is not a mahāsattva in the stage of succession, so he properly ought to question. Why is it now that Maitreya instead questions Mañjuśrī?" Although Mañjuśrī answered Maitreya, since the assembly at that time had such a doubt, it is now explained: In the past, when Candrasūryapradīpa Buddha was in secular life, he had eight sons. These eight sons were originally Mañjuśrī's disciples. Mañjuśrī converted and guided the eight sons so that they all achieved the Buddha path. The last to achieve Buddhahood among the eight sons was named Dīpaṅkara. Dīpaṅkara Buddha is Dīpaṅkara (Dingguang); Dīpaṅkara Buddha was the teacher of Śākyamuni; Śākyamuni is again the teacher of Maitreya. Thus, Mañjuśrī is Śākyamuni's grand-teacher, and with respect to Maitreya, he is his great-grand-teacher. For this reason, Mañjuśrī ought to answer, and Maitreya ought to question.