What is the ruling on purchasing from a market built on usurped land?

If it is proven that the land is usurped, then it is impermissible to buy from the market established on it, in order to prevent engaging in activity on usurped property, and because it entails aiding in oppression and remaining therein without the owner's permission. This is based on the Almighty's saying: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." Scholars have prohibited praying in a usurped place, and many of them considered such prayers invalid. They also prohibited sitting on a usurped bed, even for someone other than the usurper.