Musnad Ahmad 33:403

Abu Amir narrated to us, Fulayh narrated to us, Sa’id ibn al-Harith narrated to us, he said: We entered upon Jabir ibn Abdullah while he was praying in a single garment, wrapped in it, and his mantle was near; if he had reached for it, he would have attained it. When he finished the prayer, we asked him about that, and he said: "I only do this so that fools like you might see me, and then spread the concession that the Messenger of Allah (peace and blessings of Allah be upon him) granted regarding Jabir." Then Jabir said: I went out with the Messenger of Allah (peace and blessings of Allah be upon him) on one of his journeys. I came to him one night while he was praying in a single garment, and I had a single garment, so I wrapped myself in it and stood by his side. He said: "O Jabir, what is this wrapping? If you pray and you have a single garment, if it is wide, then wrap yourself in it; and if it is narrow, then tie it around your waist."