Sahih Bukhari
Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
Volume: 005 / Book Number: 059 / Hadith Number: 533
Narrated Al-Bara' and Ibn Abi Aufa:
On the day of Khaibar when the cooking pots were put on the fire, the Prophet said, "Turn the cooking pots upside down."