كتاب الْمَسَاجِدِ وَمَوَاضِعِ الصَّلاَةِ
5  
The Book of Mosques and Places of Prayer
(34)
Chapter: It is recommended to pray `Asr early
(34)
باب اسْتِحْبَابِ التَّبْكِيرِ بِالْعَصْرِ
Sahih Muslim 621 d

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.
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 ‏.‏
Reference : Sahih Muslim 621d
In-book reference : Book 5, Hadith 245
USC-MSA web (English) reference : Book 4, Hadith 1300
  (deprecated numbering scheme)