Sunan Ibn Majah, Chapter: The Chapters on Business Transactions

the Messenger of Allah (saw) went to the market of Nabit, and looked at it, and said: "This is not a market for you." Then we went to another market and looked at it, and said: "This is not a market for you." Then he came back to this market and walked around in it then he said: "This is your market. It will always be your market and no duty will be levied on it." (Daif)