מילון על עבודה זרה 12:3

It was stated³³Babli 6b. While trade is forbidden, the proceeds of an illegal trade are not.: If one transgressed and traded with him, it is permitted. Rebbi Jacob bar Aḥa, Rebbi Yose, in the name of Rebbi Joḥanan: Even on his holiday³⁴Disputed by the Babli 6b, Tosephta 1:9.. It was stated so:³⁵Quoted in Tosaphot 2a, s.v. אסור. When was this said? About a Gentile whom he does not know. But with a Gentile of his acquaintance it is permitted since he is flattering him. It was stated: If one enters a town and finds them celebrating, he celebrates with them because he only is flattering them.