פירוש על עבודה זרה 105:7

The amoraim discuss a case where the idol was sold to a smelter. According to one opinion, the tannaim disagree if it was sold to an idolatrous smelter. One tanna hold that since the smelter is idolatrous, he might use the metal to make another idol. But if he sold it to an Israelite, the Israelite will surely melt it down for another purpose, and thus this is annulment. While the other tanna holds that even selling it to an idolater is considered annulment.
The other amora thinks that the tannaim disagree when sold to an Israelite smelter.