God is Great. Khaibar shall face destruction. When we descend in the city-square of a people, it is a bad day for them who have been warned (and have not taken heed). He said these words thrice. The people of the town had just come out from (their houses) to go about their jobs. They said (in surprise): Muhammad has come. We captured Khaibar by force.
Sahih Muslim Book 32, Hadith 147