Even when it is permitted to rent [homes to idolaters], it is not permitted to rent to them for use as a dwelling, because they will bring idols into them, as [Deuteronomy 7:26] states: "Do not bring an abomination into your home." It is, however, permitted to rent them homes to use as storehouses.
It is forbidden to sell them fruit, grain, or other produce while it is attached to the earth. One may sell [these products] after they have been harvested or [before they have been harvested], on the condition that they will be harvested, and he must harvest them.
Why is it forbidden to sell them [land or anything attached to the land]? Because [Deuteronomy 7:2] states: "Do not be gracious with them." [This phrase can also be interpreted:] "Do not give them a resting place in the land." As long as they do not have a resting place in the land, their stay will be a temporary one.
[This prohibition also] forbids speaking about [idolaters] in a praiseworthy manner. It is even forbidden to say, "Look how beautiful that idolater's body is." How much more so is it forbidden to praise their deeds or to hold their words dear, as [the phrase states]: "Do not be gracious with them." [This phrase can also be interpreted:] "Do not look at them graciously," for doing so will cause you to draw close to them and learn from their wicked behavior.
[Also implicit in the above phrase is that] it is forbidden to give them a present. A present may, however, be given to a ger toshav, [as implied by Deuteronomy 14:21:] "You may give it to the stranger in your gates so that he may eat it; or sell it to a gentile," [i.e., to an idolater]; it should be sold, not given.