Sahih al-Bukhari 6212
Narrated Anas bin Malik:
There was a state of fear in Medina. Allah's Messenger (ﷺ) rode a horse belonging to Abu Talha (in order to 
see the matter). The Prophet (ﷺ) said, "We could not see anything, and we found that horse like a sea (fast 
in speed).
حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا يَحْيَى، عَنْ شُعْبَةَ، قَالَ حَدَّثَنِي قَتَادَةُ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ كَانَ بِالْمَدِينَةِ فَزَعٌ فَرَكِبَ رَسُولُ اللَّهِ صلى الله عليه وسلم فَرَسًا لأَبِي طَلْحَةَ فَقَالَ ‏
"‏ مَا رَأَيْنَا مِنْ شَىْءٍ، وَإِنْ وَجَدْنَاهُ لَبَحْرًا ‏"‏‏.‏