كتاب وقوت الصلاة
1  
The Times of Prayer

Urwa said that A'isha, the wife of the Prophet, may Allah bless him and grant him peace used to pray asr while the sunlight was pouring into her room, before the sun itself had become visible (i.e. because it was still high in the sky).

قَالَ عُرْوَةُ وَلَقَدْ حَدَّثَتْنِي عَائِشَةُ زَوْجُ النَّبِيِّ صلى الله عليه وسلم أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ يُصَلِّي الْعَصْرَ وَالشَّمْسُ فِي حُجْرَتِهَا قَبْلَ أَنْ تَظْهَرَ ‏.‏
Arabic/English book reference : Book 1, Hadith 2