大乘百法明門論開宗義決 1.42

1.42

但以義類相從而說者。謂三時教對不定性。佛隨根性說或前後。但雖前說對久根性。義同第三時即第三時攝。雖最後說對初根性。義同初時則初時攝。故花嚴經成道初說。義同第三時則第三時攝。

Regarding "it is merely spoken according to the congruence of meaning and category": This means that the teachings of the three periods are addressed to those of indeterminate nature. The Buddha taught earlier or later in accordance with their capacities. Even if taught earlier, if it was for those of mature capacity and its meaning aligns with the third period, it is subsumed under the third period. Even if taught last, if it was for those of initial capacity and its meaning aligns with the first period, it is subsumed under the first period. Therefore, although the Avataṃsaka-sūtra was spoken at the beginning of awakening, because its meaning aligns with the third period, it is subsumed under the third period.