Musnad Ahmad 33:463

Rawh narrated to us, Zakariya ibn Ishaq narrated to us, ‘Amr ibn Dinar narrated to us, he said: I heard Jabir ibn ‘Abdullah saying: "The Prophet, may Allah bless him and grant him peace, was carrying stones for the Ka‘bah with them, and he was wearing his lower garment (izar). His uncle al-‘Abbas said to him: 'O son of my brother, if you were to untie your lower garment and place it over your shoulders to cushion the stones.' He said: 'So he untied it and placed it over his shoulders, then he fell unconscious. He was never seen naked after that day.'"