152. Idols Belonging to Non-Jews and to Jews
Avodas Kochavim 7:3
We are not permitted to benefit from an animal that was wholly offered to an idol, not even from its excrement, bones, horns, hooves, or hide. For example, if the hide of an animal shows signs that it was offered to an idol, such as if it has a round hole in the place through which the heart would have been extracted, then it is forbidden to benefit from those hides.
Avodas Kochavim 7:4
There is difference between an idol belonging to a non-Jew and one belonging to a Jew: it is prohibited to derive benefit from the idol of a non-Jew as soon it has been made, as per Deuteronomy 7:25, “You must burn the graven images of their gods with fire.” This means that they are considered idols as soon as they have been fashioned. A Jew’s idol, however, is not prohibited until he worships it, as per Deuteronomy 27:15, “Cursed be the one who makes an idol... and sets it up in secret.” We see that it does not become prohibited until the Jew does secret things, i.e., worships it. The accessories of an idol do not become prohibited until they are actually used in the service of the idol, whether they belong to a Jew or a non-Jew.