Responsa על עבודה זרה 12:22

Nevertheless, it seems that it would be forbidden for a Jew to sacrifice their paschal lamb, because this is an established commandment for them, and we do not leave Noahides to add on to their seven commandments. For it is stated in the chapter “Arba Mitot” (Sanhedrin 58b): “A Noahide who observes Shabbat is liable for death.” The same applies to any other commandment, as Maimonides wrote in the Laws of Kings (10:9). If so, how can a Jew slaughter on their behalf? He must prevent them! Indeed, the Sages stated (Avoda Zara 6b): “It is forbidden to hand to a Noahide a limb from a living animal; even though one does not transgress “placing a stumbling block before the blind” unless they are standing on opposite sides of the river, as noted in the first chapter of Avoda Zara (ibid.), it is nevertheless forbidden to aid them, for indeed there is a duty to separate them [from the violation]. Tosafot stated similarly in the first chapter of Shabbat. And if this lamb is akin to the paschal offering, a commemoration of the Akeida, then it is indeed a sacrifice. Non-Jews may offer sacrifices on their altars as long as it is not a fixed commandment. Therefore, if a Jew slaughters it, he is slaughtering sacred property outside the Temple precincts, and thereby incurs the punishment of extirpation (karet), even if the sacred property is the offering of a gentile. Similarly, one who eats from it is eating from sacred property outside of the Temple precincts.

R. Hayyim Eliezer asked his nephew the following questions:
(1) Why is it permissible to instruct a Gentile to bring willows for the festival of Tabernacles, since a Gentile is forbidden to rob, and these willows are usually robbed by him? We induce the Gentile to sin when we purchase the willows from him, and if we would refrain from buying the willows from him, he would then have no reason to rob them.
(2) Why is it necessary for one who purchased a house that was confiscated by the authorities, from a Jew, to return it to the original owner. Should this not be similiar to a case of an article that was washed away by a river, and is considered abandoned property, although the owner refuses to concede its loss?
R. Shalom answers:
(1) When a Jew purchases willows from a Gentile, the former is not guilty of abetting the Gentile to sin, as the latter would have taken these willows anyway, since he can sell them to another Gentile for other purposes such as barrel covers, etc.
(2) Unlike an article that was washed away by a river, a house that was confiscated by the authorities is irretrievable only to the original owner. Furthermore, one does not easily abandon real estate, as there is always hope for its ultimate return, through justice or other means.