“I came to the Messenger of Allah ﷺ and gave him my pledge, and the buttons of his shirt were undone.”
أَتَيْتُ رَسُولَ اللَّهِ ﷺ فَبَايَعْتُهُ وَإِنَّ زِرَّ قَمِيصِهِ لَمُطْلَقٌ قَالَ عُرْوَةُ فَمَا رَأَيْتُ مُعَاوِيَةَ وَلاَ ابْنَهُ فِي شِتَاءٍ وَلاَ صَيْفٍ إِلاَّ مُطْلَقَةً أَزْرَارُهُمَا
I came to the Messenger of Allah ﷺ with a company of Muzainah and we swore allegiance to him. The buttons of his shirt were open. I swore allegiance to him and I put my hand inside the collar of his shirt and felt the seal. 'Urwah said: I always saw Mu'awiyah and his son opening their buttons of the collar during winter and summer. They never closed their buttons. (Using translation from Abū Dāʾūd 4082)
أَتَيْتُ فِي رَهْطٍ مِنْ مُزَيْنَةَ فَبَايَعْنَا وَإِنَّ قَمِيصَهُ لَمُطْلَقٌ فَبَايَعْتُهُ فَأَدْخَلْتُ يَدِي مِنْ جَيْبِ الْقَمِيصِ فَمَسِسْتُ الْخَاتَمَ قَالَ عُرْوَةُ فَمَا رَأَيْتُ مُعَاوِيَةَ وَلَا اَبَنهُ شِتَاءً وَلَا حَرًّا إِلَّا مُطْلِقَيْ أَزْرَارِهِمَا لَا يَزُرَّانِ أَبَدًا