Sahih Bukhari Volume 4, Book 56, Hadith 2976

حَدَّثَنَا قُتَيْبَةُ، حَدَّثَنَا حَاتِمُ بْنُ إِسْمَاعِيلَ، عَنْ يَزِيدَ بْنِ أَبِي عُبَيْدٍ، عَنْ سَلَمَةَ بْنِ الأَكْوَعِ ـ رضى الله عنه ـ قَالَ كَانَ عَلِيٌّ ـ رضى الله عنه ـ تَخَلَّفَ عَنِ النَّبِيِّ صلى الله عليه وسلم فِي خَيْبَرَ، وَكَانَ بِهِ رَمَدٌ، فَقَالَ أَنَا أَتَخَلَّفُ عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم فَخَرَجَ عَلِيٌّ فَلَحِقَ بِالنَّبِيِّ صلى الله عليه وسلم، فَلَمَّا كَانَ مَسَاءُ اللَّيْلَةِ الَّتِي فَتَحَهَا فِي صَبَاحِهَا، فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ لأُعْطِيَنَّ الرَّايَةَ ـ أَوْ قَالَ لَيَأْخُذَنَّ ـ غَدًا رَجُلٌ يُحِبُّهُ اللَّهُ وَرَسُولُهُ ـ أَوْ قَالَ يُحِبُّ اللَّهَ وَرَسُولَهُ ـ يَفْتَحُ اللَّهُ عَلَيْهِ ‏"‏‏.‏ فَإِذَا نَحْنُ بِعَلِيٍّ، وَمَا نَرْجُوهُ، فَقَالُوا هَذَا عَلِيٌّ، فَأَعْطَاهُ رَسُولُ اللَّهِ صلى الله عليه وسلم، فَفَتَحَ اللَّهُ عَلَيْهِ‏

Narrated By Salama bin Al-Akwa : Ali remained behind the Prophet during the battle of Khaibar as he way suffering from some eye trouble but then he said, "How should I stay behind Allah's Apostle?" So, he set out till he joined the Prophet. On the eve of the day of the conquest of Khaibar, Allah's Apostle said, "(No doubt) I will give the flag or, tomorrow, a man whom Allah and His Apostle love or who loves Allah and His apostle will take the flag. Allah will bestow victory upon him." Suddenly 'Ali joined us though we were not expecting him. The people said, "Here is 'Ali. "So, Allah's Apostle gave the flag to him and Allah bestowed victory upon him.