Messenger of Allah ﷺ reached Khaibar in the early morning and the people of Khaibar came out with their spades, and when they saw the Prophet ﷺ they said, "Muhammad and his army!" and returned hurriedly to take refuge in the fort. The Prophet ﷺ raised his hands and said, "Allah is Greater! Khaibar is ruined ! If we approach a nation, then miserable is the morning of those who are warned."
سَمِعْتُ أَنَسَ بْنَ مَالِكٍ ؓ يَقُولُ صَبَّحَ رَسُولُ اللَّهِ ﷺ خَيْبَرَ بُكْرَةً وَقَدْ خَرَجُوا بِالْمَسَاحِي فَلَمَّا رَأَوْهُ قَالُوا مُحَمَّدٌ وَالْخَمِيسُ وَأَحَالُوا إِلَى الْحِصْنِ يَسْعَوْنَ فَرَفَعَ النَّبِيُّ ﷺ يَدَيْهِ وَقَالَ اللَّهُ أَكْبَرُ خَرِبَتْ خَيْبَرُ إِنَّا إِذَا نَزَلْنَا بِسَاحَةِ قَوْمٍ فَسَاءَ صَبَاحُ الْمُنْذَرِينَ