That the Messenger of Allah (ﷺ) said: "The dweller of the town is not to sell for the Bedouin."

There are narrations on this topic from Talhah, Jabir, Anas, Ibn 'Abbas, Hakim bin Abi Yazid from his father, 'Amr bin 'Awf Al-Muzani the grandfather of Kathir bin 'Abdullah, and a man from the Companions of the Prophet (ﷺ).

Jami` at-Tirmidhi Book 14, Hadith 21