Language:
كتاب الجهاد والسير
56  
Fighting for the Cause of Allah (Jihaad)
(165)
Chapter: If the people get frightened at night
(165)
باب إِذَا فَزِعُوا بِاللَّيْلِ
Sahih al-Bukhari 3040

Narrated Anas:

Allah's Messenger (ﷺ) was the (most handsome), most generous and the bravest of all the people. Once the people of Medina got frightened having heard an uproar at night. So, the Prophet (ﷺ) met the people while he was riding an unsaddled horse belonging to Abu Talha and carrying his sword (slung over his shoulder). He said (to them), "Don't get scared, don't get scared." Then he added, "I found it (i.e the horse) very fast."

حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا حَمَّادٌ، عَنْ ثَابِتٍ، عَنْ أَنَسٍ ـ رضى الله عنه ـ قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم أَحْسَنَ النَّاسِ، وَأَجْوَدَ النَّاسِ، وَأَشْجَعَ النَّاسِ، قَالَ وَقَدْ فَزِعَ أَهْلُ الْمَدِينَةِ لَيْلَةً سَمِعُوا صَوْتًا، قَالَ فَتَلَقَّاهُمُ النَّبِيُّ صلى الله عليه وسلم عَلَى فَرَسٍ لأَبِي طَلْحَةَ عُرْىٍ، وَهُوَ مُتَقَلِّدٌ سَيْفَهُ فَقَالَ ‏"‏ لَمْ تُرَاعُوا، لَمْ تُرَاعُوا ‏"‏‏.‏ ثُمَّ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ وَجَدْتُهُ بَحْرًا ‏"‏‏.‏ يَعْنِي الْفَرَسَ‏.‏
Reference : Sahih al-Bukhari 3040
In-book reference : Book 56, Hadith 246
USC-MSA web (English) reference : Vol. 4, Book 52, Hadith 277
  (deprecated numbering scheme)