The Book on Military Expeditions

Narrated Anas:

"When the Messenger of Allah (ﷺ) set out for Khaibar, he approached it at night and when he came to a people during the night, he would not attack them until morning. So when the morning came, the Jews came out with their shovels and baskets, then when they saw him, they said: 'Muhammad! By Allah Muhammad has come with the Khamis (an army).' So the Messenger of Allah (ﷺ) said: 'Allahu Akbar! Khaibar is destroyed, for whenever we approach the land of people - then what an evil morning for those who have been warned.'"