Sahih al-Bukhari, Hadith 3865 ⓘ

Narrated `Abdullah bin `Umar: When `Umar embraced Islam, all The (disbelieving) people gathered around his home and said, "`Umar has embraced Islam." At that time I was still a boy and was on the roof of my house. There came a man wearing a cloak of Dibaj (i.e. a kind of silk), and said, "`Umar has embraced Islam. Nobody can harm him for I am his protector." I then saw the people going away from `Umar and asked who the man was, and they said, "Al-`As bin Wail."

حَدَّثَنَا عَلِيُّ بْنُ عَبْدِ اللَّهِ، حَدَّثَنَا سُفْيَانُ، قَالَ عَمْرُو بْنُ دِينَارٍ سَمِعْتُهُ قَالَ قَالَ عَبْدُ اللَّهِ بْنُ عُمَرَ ـ رضى الله عنهما ـ لَمَّا أَسْلَمَ عُمَرُ اجْتَمَعَ النَّاسُ عِنْدَ دَارِهِ وَقَالُوا صَبَا عُمَرُ‏.‏ وَأَنَا غُلاَمٌ فَوْقَ ظَهْرِ بَيْتِي، فَجَاءَ رَجُلٌ عَلَيْهِ قَبَاءٌ مِنْ دِيبَاجٍ فَقَالَ قَدْ صَبَا عُمَرُ‏.‏ فَمَا ذَاكَ فَأَنَا لَهُ جَارٌ‏.‏ قَالَ فَرَأَيْتُ النَّاسَ تَصَدَّعُوا عَنْهُ فَقُلْتُ مَنْ هَذَا قَالُوا الْعَاصِ بْنُ وَائِلٍ‏.‏