Fiqh-us-Sunnah Volume 4, Funerals and Dhikr, Fiqh 4.142B.

Section : It is Preferred to have Companions for the Journey.

Ibn ‘Umar reported that the Prophet, peace be upon him, forbade loneliness, i.e., that a man should sleep alone at night, or go on a journey alone. (Ahmad)

Umar ibn Shu’aib reported from his father and he from his grandfather that the Prophet, peace be upon him, said, “A single horseman (traveller) is a devil, two are two devils, but three are a caravan.”