thousand, and a force of twelve thousand will never be defeated for being too few.” Narrated by Abū Dāwūd and al-Tirmidhī, who graded it ḥasan.

[Explanation]
The compiler—may Allah have mercy on him—states in his book Riyāḍ al-Ṣāliḥīn, in the chapter entitled “The Recommendation of Travelling with Companions and Appointing One of Them as Leader.” This chapter contains two issues.

First, a person should have companions on a journey and not travel alone. For that reason the Prophet ﷺ said, “If people knew what I know about the dangers of solitude, no rider would ever travel at night by himself.” In other words, a person should never set out on a journey by himself, for he may fall ill, lose consciousness, be attacked, or be struck by some other calamity, and then no one would be with him to defend him, notify others, and so forth.

This applies to journeys in which genuine isolation is expected. As for the busy highways on which scarcely a minute passes without another car going by, then even if someone is alone in his vehicle he does not come under this ruling, for such a trip is not deemed solitary travel. The roads nowadays between provinces and from one city to another are heavily trafficked—and the same principle applies.