Companions of the Prophet
حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا يَحْيَى، عَنْ إِسْمَاعِيلَ، حَدَّثَنَا قَيْسٌ، قَالَ قَالَ عَبْدُ اللَّهِ مَا زِلْنَا أَعِزَّةً مُنْذُ أَسْلَمَ عُمَرُ.Narrated `Abdullah:We have been powerful since `Umar embraced Islam
From Sahih al-Bukhari, whose reports the scholars accept as authentic.