Times of the Prayers
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ، عَنْ مَالِكٍ، عَنْ إِسْحَاقَ بْنِ عَبْدِ اللَّهِ بْنِ أَبِي طَلْحَةَ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ كُنَّا نُصَلِّي الْعَصْرَ ثُمَّ يَخْرُجُ الإِنْسَانُ إِلَى بَنِي عَمْرِو بْنِ عَوْفٍ فَنَجِدُهُمْ يُصَلُّونَ الْعَصْرَ.Narrated Anas bin Malik:We used to pray the `Asr prayer and after that if someone happened to go to the tribe of Bani `Amr bin `Auf, he would find them still praying the `Asr (prayer)
From Sahih al-Bukhari, whose reports the scholars accept as authentic.