"You shall not covet your neighbor's house"—Exodus 20:17.
It is forbidden to devise plots in pursuit of acquiring a fellow's property or possession [that he is reluctant to part with. E.g., by harassing the owner of the item to sell it, or retaining friends to go and talk him into selling it].
One who does so and ends up acquiring the item, even if he pays much money for it, has transgressed this biblical prohibition.
