瑜伽論記 4.388

4.388

觀察有學未離欲下，別釋三等至。俱住二世者，現在未來識俱有轉故。唯住他世者，唯未來世識有轉故。俱無所住者，二世無轉故。

From 'observing learners who have not yet departed from desire' onward, it individually explains the three attainments. 'Abiding in both worlds': because consciousness operates in both the present and the future. 'Abiding only in the other world': because consciousness operates only in the future world. 'Abiding in neither': because it does not operate in either of the two worlds.