ENOfficial
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).
Source: sunnah.com
Other translations
Arabic
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 ".
sunnah.com