Abu Qatadah (May Allah be pleased with him) reported:
When the Messenger of Allah (ﷺ) encamped at night during a journey, he would lie down on his right side, and when he stayed a little before dawn he would raise his forearm and place his head on the palm of his hand.[Muslim].
App reference: Book 8, Hadith 8
Arabic/English book reference: Book 8, Hadith 963