俱舍論記 18.138

18.138

「由有伴故者至為助伴」者，釋由有伴故。謂作不善業道時，還以不善業道為其助伴。故《正理》云「如盜他財，復污他室，殺他子等。」又《婆沙》二十四云「復次不善業以不善業為眷屬者具二種，以善業為眷屬者唯造作。」

"Through having an accompaniment ... serving as its companions": this explains [the condition of] being "through having an accompaniment." That is to say, when performing an unvirtuous course of action, one further uses unvirtuous courses of action as its companions. Thus the Nyāyānusāra states: "As when one steals another's wealth, further defiles another's household, murders another's child, and so forth." Furthermore, the Mahāvibhāṣā, fascicle 24, states: "Furthermore, an unvirtuous action that has unvirtuous actions as its retinue possesses both designations; one that has wholesome actions as its retinue is only 'performed.'"