Abu Tha'labah Al-Khushani (May Allah be pleased with him) reported:
Whenever the people encamped during the journey, they would disperse in the mountain passes and valleys. (When) the Messenger of Allah (ﷺ) noticed this he said, "Your act of scattering in the mountain passes and valleys is from Satan." Afterwards the Companions kept close together whenever they encamped.[Abu Dawud].