Jami` at-Tirmidhi, Volume 3, Book 21, Hadith 1673 (DarusSalam) ⓘ
Narrated Ibn 'Umar: That the Messenger of Allah said: "If the people knew what I know about being alone, then a rider would not journey at night." - meaning alone.
حَدَّثَنَا أَحْمَدُ بْنُ عَبْدَةَ الضَّبِّيُّ الْبَصْرِيُّ، حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنْ عَاصِمِ بْنِ مُحَمَّدٍ، عَنْ أَبِيهِ، عَنِ ابْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " لَوْ أَنَّ النَّاسَ يَعْلَمُونَ مَا أَعْلَمُ مِنَ الْوَحْدَةِ مَا سَرَى رَاكِبٌ بِلَيْلٍ " . يَعْنِي وَحْدَهُ .
also referenced under: Hadith 1673 (Reference) & Book 23, Hadith 4 (In-Book)