Sahih al-Bukhari 7256
Narrated `Umar:
There was a man from the Ansar (who was a friend of mine). If he was not present in the company of 
Allah's Messenger (ﷺ) I used to be present with Allah's Messenger (ﷺ), I would tell him what I used to hear from 
Allah's Messenger (ﷺ), and when I was absent from Allah's Messenger (ﷺ) he used to be present with him, and he 
would tell me what he used to hear from Allah's Messenger (ﷺ) .
حَدَّثَنَا سُلَيْمَانُ بْنُ حَرْبٍ، حَدَّثَنَا حَمَّادُ بْنُ زَيْدٍ، عَنْ يَحْيَى بْنِ سَعِيدٍ، عَنْ عُبَيْدِ بْنِ حُنَيْنٍ، عَنِ ابْنِ عَبَّاسٍ، عَنْ عُمَرَ ـ رضى الله عنهم ـ قَالَ وَكَانَ رَجُلٌ مِنَ الأَنْصَارِ إِذَا غَابَ عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم وَشَهِدْتُهُ أَتَيْتُهُ بِمَا يَكُونُ مِنْ رَسُولِ اللَّهِ صلى الله عليه وسلم وَإِذَا غِبْتُ عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم وَشَهِدَ أَتَانِي بِمَا يَكُونُ مِنْ رَسُولِ اللَّهِ صلى الله عليه وسلم‏.‏