Sahih al-Bukhari 4197

Arabic

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يُوسُفَ، أَخْبَرَنَا مَالِكٌ، عَنْ حُمَيْدٍ الطَّوِيلِ، عَنْ أَنَسٍ ـ رضى الله عنه أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم أَتَى خَيْبَرَ لَيْلاً، وَكَانَ إِذَا أَتَى قَوْمًا بِلَيْلٍ لَمْ يُغِرْ بِهِمْ حَتَّى يُصْبِحَ، فَلَمَّا أَصْبَحَ خَرَجَتِ الْيَهُودُ بِمَسَاحِيهِمْ وَمَكَاتِلِهِمْ، فَلَمَّا رَأَوْهُ قَالُوا مُحَمَّدٌ وَاللَّهِ، مُحَمَّدٌ وَالْخَمِيسُ، فَقَالَ النَّبِيُّ صلى الله عليه وسلم ‏ "‏ خَرِبَتْ خَيْبَرُ، إِنَّا إِذَا نَزَلْنَا بِسَاحَةِ قَوْمٍ فَسَاءَ صَبَاحُ الْمُنْذَرِينَ ‏"‏‏.‏

English translation

Narrated Anas:Allah's Messenger (ﷺ) reached Khaibar at night and it was his habit that, whenever he reached the enemy at night, he will not attack them till it was morning. When it was morning, the Jews came out with their spades and baskets, and when they saw him(i.e. the Prophet (ﷺ) ), they said, "Muhammad! By Allah! Muhammad and his army!" The Prophet (ﷺ) said, "Khaibar is destroyed, for whenever we approach a (hostile) nation (to fight), then evil will be the morning for those who have been warned

Reference: Sahih al-Bukhari 4197, Book of Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi). English translation by Dr. Muhammad Muhsin Khan.