Does zakat become obligatory on real estate purchased by a merchant to endow it for the poor, if a year passes while it is vacant?

If a man buys real estate with the intention of it being an endowment (waqf), not for trade, then there is no zakat on it. This is because it is not considered a trade commodity. Rather, it is in the same category as something prepared for personal use (qinyah), based on the Prophet's (peace be upon him) saying: "There is no sadaqah (zakat) on a Muslim for his slave or his horse." Furthermore, wealth endowed for the poor is not subject to zakat.