صَحِيحُ مُسْلِمٍ
Sahih Muslim 621 d
The Book of Mosques and Places of Prayer
It is recommended to pray `Asr early
وَحَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى 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 فَيَجِدُهُمْ يُصَلُّونَ الْعَصْرَ .
Anas b. Malik reported: We used to offer the afternoon prayer (at such a time) that a person would go to Bani 'Amr b. Auf and he would find them busy offering the afternoon prayer.
Sahih Muslim, 621 dSahihصحيح