Evidence that he wraps himself in it if it is wide, and if it is narrow he wears it as a waist wrapper and his prayer is valid

Sa'id bin al-Harith narrates: We came as a group to Sayyiduna Jabir bin Abdullah (may Allah be pleased with them both). He was praying wrapped in a single garment while his upper sheet was lying close by him; had he wanted to take it, he could have reached it. When he finished the prayer with the salam, we asked him about his praying in a single garment, and he said: I do this so that fools like you see me and spread from Jabir a concession that the Messenger of Allah (peace and blessings be upon him) granted him. I was with the Messenger of Allah (peace and blessings be upon him) on one of his journeys, and one night I came to him (peace and blessings be upon him) for some personal matter of mine. I saw the Messenger of Allah (peace and blessings be upon him) praying, and I was wearing only a single garment, so I wrapped that garment around myself and stood beside him. When he (peace and blessings be upon him) finished the prayer with the salam, he said: "O Jabir! What brings you at night?" So I told him my need. The Messenger of Allah (peace and blessings be upon him) said: "O Jabir! What is this wrapping that I saw?" I said: "O Messenger of Allah! It was one garment, and a tight one too." He (peace and blessings be upon him) said: "When you pray with only one garment on you, if it is ample, wrap it around yourself, and if it is tight, tie it on as a waist-wrapper."

Ubadah bin al-Walid bin al-Samit narrates: We came to Sayyiduna Jabir bin Abdullah (may Allah be pleased with them both) in his mosque. He was praying wrapped in a single garment. I stepped over the people until I reached him and sat between him and the qiblah, and I said: "May Allah Almighty have mercy on you! Are you praying in one garment while your waist-wrapper is right here by your side?" He said: "I want fools like you to come to me and see how I do it, so that they too do the same."
The Messenger of Allah (peace and blessings be upon him) stood up for prayer (on a military expedition), and I was wearing a striped sheet. I began turning its ends over (to tie it at my neck), but it would not reach. I turned it upside down. Then I crossed its ends (that is, the right end to the left side and the left end to the right side). Then I bent my neck to hold it in place (to stop it from falling). Then I came and stood on the left side of the Messenger of Allah (peace and blessings be upon him); he took me by my hand, turned me around and made me stand on his right side.
Then Ibn Sakhr (may Allah be pleased with him) came and stood on his left side. He (peace and blessings be upon him) took hold of both of us and made us stand behind him. We stood behind him (peace and blessings be upon him). The Messenger of Allah (peace and blessings be upon him) kept looking at me, but I could not understand; then I understood. He (peace and blessings be upon him) gestured to me, meaning: tie on the waist-wrapper. When the Messenger of Allah (peace and blessings be upon him) finished the prayer, he said: "Jabir!" I said: "Here I am, O Messenger of Allah!" He (peace and blessings be upon him) said: "When the garment is ample, put its right end over the left shoulder and its left end over the right shoulder; and if the garment is small, tie it around your waist."

(a) It is narrated from the Mother of the Believers, Sayyidah Maymunah (may Allah be pleased with her), that the Messenger of Allah (peace and blessings be upon him) would sometimes pray in a large sheet, part of which was over me and part over him, even when I was menstruating.
(b) A similar hadith is also established from Sayyidah Aishah (may Allah be pleased with her).
(c) In this hadith there is evidence that praying in a single garment is permissible, even if no part of that garment is on the person's shoulders.