俱舍論頌疏論本 10.72

10.72

'Being contaminated, they extend to the three realms': although contact, volition, and the third extend to the uncontaminated, here the nature of food takes only the contaminated, because it nourishes existence. If they were uncontaminated dharmas, they would destroy existences; therefore they are not food. The three foods of contact and so forth are subsumed across the three realms.