פירוש על עבודה זרה 82:9

R. Yohanan says that the analogy is not correct. Images may not have been worshipped, and when they broke, they may have been annulled. Thus there are two doubts and in cases of a double doubt, we can rule leniently. But in the case of a broken piece of an idol, it may not have been annulled. There is only one doubt, and one doubt is not sufficient to remove from the certainty that the idol was worshipped.