Musnad Ahmad 126:1

Hassan—meaning al-Ashyab—and Abu al-Nadr narrated to us, they said: Zuhayr narrated to us, from ‘Urwah ibn ‘Abd Allah ibn Qushayr, from Mu‘awiyah ibn Qurrah, from his father. Abu al-Nadr said in his narration: Zuhayr narrated to us, ‘Urwah ibn ‘Abd Allah ibn Qushayr Abu Muhal al-Ju‘fi narrated to us, he said: Mu‘awiyah ibn Qurrah narrated to me, from his father, who said: "I came to the Messenger of Allah (may Allah bless him and grant him peace) among a group from Muzaynah, and we pledged allegiance to him, while his shirt was unbuttoned." He said: "So we pledged allegiance to him, then I inserted my hand into the collar of his shirt and touched the seal (the Seal of Prophethood)." ‘Urwah said: "I never saw Mu‘awiyah nor his son—Hassan said: meaning Abu Iyas—in winter or summer ever with their buttons fastened; they would never button them."