(4) باب مَا جَاءَ فِي كَرَاهِيَةِ أَنْ يُسَافِرَ الرَّجُلُ وَحْدَهُ
Narrated Ibn 'Umar:
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.
Reference: Jami` at-Tirmidhi 1673
In-book reference: Book 23, Hadith 4
English translation: Vol. 3, Book 21, Hadith 1673