Language:
كتاب مناقب الأنصار
63  
Merits of the Helpers in Madinah (Ansaar)
(35)
Chapter: The conversion ‘Umar رضي الله عنه to Islam
(35)
باب إِسْلاَمِ عُمَرَ بْنِ الْخَطَّابِ رضى الله عنه
Sahih al-Bukhari 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.‏
Reference : Sahih al-Bukhari 3865
In-book reference : Book 63, Hadith 90
USC-MSA web (English) reference : Vol. 5, Book 58, Hadith 205
  (deprecated numbering scheme)