He attributed it to the Prophet ﷺ, who said, "If people knew what I know about being alone, no rider would travel by night on his own."
حدثنا سفيان بن عيينة عن عاصم عن أبيه
يبلغ به النبي ﷺ قال لو علم الناس ما في الوحدة ما أعلم ما سرى راكب بليل وحده
Its isnad is sahih. Asim is Ibn Muhammad bin Zayd bin Abdullah bin Umar bin Khattab. The hadith is a repetition of 5252.