That the Messenger of Allah ﷺ said: "If the people knew what I know about being alone, then a rider would not journey at night." - meaning alone.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ لَوْ أَنَّ النَّاسَ يَعْلَمُونَ مَا أَعْلَمُ مِنَ الْوَحْدَةِ مَا سَرَى رَاكِبٌ بِلَيْلٍ يَعْنِي وَحْدَهُ  

From his father, from his grandfather that the Messenger of Allah ﷺ said: "The (lone) rider is a Shaitan, and two raiders are two Shaitan. Three is a travelling party.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ الرَّاكِبُ شَيْطَانٌ وَالرَّاكِبَانِ شَيْطَانَانِ وَالثَّلاَثَةُ رَكْبٌ