Hadith 581
Sayyiduna Abdullah bin Abi Awfa Aslami, may Allah be pleased with him, says: The Messenger of Allah, peace and blessings be upon him, attacked the people of Khaybar while they were unaware, so they said: By Allah! This is Muhammad, peace and blessings be upon him, and his army. The Prophet, peace and blessings be upon him, said: "Allah is the Greatest! Khaybar is destroyed. Whenever we descend into the courtyard of a people, the morning of those who have been warned becomes evil."