瑜伽論記 18.314

18.314

言又黑白業至總立黑白者，三藏云：剎那剎那前後相生名為生類，謂前剎那生於善心，即於後念起不善心為眷屬者，於此前善心業處不善為伴黑白俱有，故名雜業。

Regarding the passage from "furthermore, black-and-white karma…" to "collectively establish black-and-white," the Tripiṭaka Master says: arising in succession moment by moment is called 'class of arising.' That is to say, a wholesome mind arises in a prior moment, and in the subsequent thought an unwholesome mind arises as its companion; at the locus of that prior wholesome mental karma, the unwholesome serves as an accompaniment so that both black and white are present, hence it is called mixed karma.