פירוש על עבודה זרה 38:15

One should not make jewelry for an idolater lest they use it to decorate their idols. Rabbi Eliezer says that one may sell jewelry to them but not give it for free. This opinion is perplexing because usually if we are concerned that the actions of the Jew might encourage idolatry, the fact that he profits does not make it more permissible. There are some versions of the mishnah that do not include this line.

The mishnah now begins to discuss selling them land and things attached to the land. One should not sell them things attached to the land, such as trees, since this might give them a stake in the land as well. Once the item has been cut down, it is permitted. Rabbi Judah is more lenient and allows something to be sold while it is attached, as long as it is stipulated that it will be cut down.