It is narrated from Sayyiduna Jubayr bin Mut'im (may Allah be pleased with him) that a man came to the Prophet (peace and blessings be upon him) and said: O Messenger of Allah! Which are the worst places? He (peace and blessings be upon him) said: "I do not know." Then when Jibril (peace be upon him) came, he (peace and blessings be upon him) asked: "O Jibril! Which are the worst places?" He said: I do not know until I enquire of my Lord. Then he went and stayed as long as Allah willed, then came and said: O Muhammad! You asked me which are the worst places, and I said that I did not know; then I asked my Lord which are the worst places, and Allah said: "Their markets." Amr bin Thabit (Ibn Abi al-Miqdam al-Kufi) does not meet the condition of the two Shaykhs; I have mentioned it only as a shahid (supporting narration), and Abdullah bin al-Mubarak's narrating from him is what prompted me to mention it.