妙法蓮華經玄贊 2.252

2.252

贊曰：此明王化。無一世界有二輪王，如何今言各領四天下？今解八子相繼統領，非一時也。然以義通，劫減佛興、劫增輪王方出，如何彼佛有子而作輪王？此乃應紹輪帝王四天下，如釋迦佛應為金輪王，非正已受，劫漸減故，由此增至八萬歲儴佉方出。第十劫初減彌勒方出，輪王命長故見彌勒。或此報佛與化佛殊，報佛未必於減劫出，故可有子得作輪王。妙光化八子堅固菩提得入八地，故知報佛亦為菩薩先說無量義竟，為聲聞後說法華，如《鼓音王經》阿彌陀佛有妻子故。

The commentary says: This explains their royal governance. In no single world are there two wheel-turning kings; how can it now be said that each ruled over the four continents? It is now explained that the eight sons ruled in succession, not at the same time. However, to harmonize this through meaning: in a decreasing kalpa a buddha arises, while in an increasing kalpa a wheel-turning king appears; how could that buddha have sons who became wheel-turning kings? These were ones who should have succeeded as wheel-turning emperors ruling the four continents, just as Śākyamuni Buddha should have been a golden wheel-turning king, not that they had actually already received it, because the kalpa was gradually decreasing; for this reason, only when it increases to eighty thousand years will Śaṅkha appear. At the beginning of the decrease of the tenth kalpa, Maitreya will appear; because the wheel-turning king has a long life, he will see Maitreya. Or, this reward buddha differs from an emanation buddha: a reward buddha does not necessarily appear in a decreasing kalpa, so it is possible for him to have sons who became wheel-turning kings. Varaprabha converted the eight sons so that they became firm in bodhi and attained entry into the eighth ground; thus we know that a reward buddha also first expounds the Anantanirdeśa for bodhisattvas and afterwards expounds the Lotus Sūtra for śrāvakas, just as in the Drum Sound King Sūtra, Amitābha Buddha has a wife and children.