Anas bin Malik reported,

The Messenger of Allah ﷺ reached Khaybar in the early morning. The people of Khaybar came out toward us carrying their spades, but when they saw us they cried out, "Muhammad and his army!" and ran back to their fortress in panic.The Messenger of Allah ﷺ raised his hands and said, "Allah is the Greatest! Allah is the Greatest! Khaybar is destroyed. When we descend upon a people's territory, "evil is the morning of those who were warned" [Saffat 37:177]."We captured some donkeys there and cooked them, but then a herald of the Prophet ﷺ called out, "Allah and His Messenger forbid you the flesh of donkeys, for it is impure."

أخبرنا محمد بن عبد الله بن يزيد قال حدثنا سفيان عن أيوب عن محمد

عن أنس قال

صبح رسول الله ﷺ خيبر فخرجوا إلينا ومعهم المساحي فلما رأونا قالوا محمد والخميس ورجعوا إلى الحصن يسعون فرفع رسول الله ﷺ يديه ثم قال الله أكبر الله أكبر خربت خيبر إنا إذا نزلنا بساحة قوم {فساء صباح المنذرين} فأصبنا فيها حمرا فطبخناها فنادى منادي النبي ﷺ فقال إن الله عز وجل ورسوله ينهاكم عن لحوم الحمر فإنها رجس