大般涅槃經義記 5.288

5.288

又問：行有同皆是業，何故過去偏彰其行，現在說有？理實亦齊，為分世別，隱顯異論，等是隱顯，非無所以。過去之業集起已竟，是故當相說之為行；未來之果由業故有，是故就能說之為有。

Another question: Karmic formations and becoming are both alike karma; why are karmic formations exclusively displayed in the past, while becoming is stated in the present? In principle they are also equal; to distinguish the lifetimes, they are discussed differently in terms of hidden and manifest. Although equal in being hidden and manifest, it is not without reason. The karma of the past has already completed its gathering and arising, and therefore according to its characteristic it is spoken of as karmic formations; the fruits of the future exist due to karma, and therefore based on its capacity it is spoken of as becoming.