The Book of the Times (of Prayer)
6/36. Chapter:
Concession Allowing Prayer After 'Asr
Sunan an-Nasai
أَخْبَرَنَا إِسْمَاعِيلُ بْنُ مَسْعُودٍ، عَنْ خَالِدِ بْنِ الْحَارِثِ، عَنْ شُعْبَةَ، عَنْ أَبِي إِسْحَاقَ، قَالَ سَمِعْتُ مَسْرُوقًا، وَالأَسْوَدَ، قَالاَ نَشْهَدُ عَلَى عَائِشَةَ أَنَّهَا قَالَتْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم إِذَا كَانَ عِنْدِي بَعْدَ الْعَصْرِ صَلاَّهُمَا .
It was narrated that Abu Ishaq said: "I heard Masruq and Al-Aswad say: We bear witness that 'Aishah said: 'When the Messenger of Allah (ﷺ) was with me after 'Asr, he would pray them (these two Rak'ahs).'"
Reference : Sunan an-Nasa'i 576In-book reference : Book 6, Hadith 83English translation : Vol. 1, Book 6, Hadith 577