Sunan an-Nasa'i, Volume 1, Book 6, Hadith 575 (DarusSalam)

It was narrated that Hisham said: "My father told me: 'Aishah said: 'The Messenger of Allah never neglected to pray two Rak'ahs after 'Asr in my house.'"

أَخْبَرَنَا عُبَيْدُ اللَّهِ بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا يَحْيَى، عَنْ هِشَامٍ، قَالَ أَخْبَرَنِي أَبِي قَالَ، قَالَتْ عَائِشَةُ مَا تَرَكَ رَسُولُ اللَّهِ صلى الله عليه وسلم السَّجْدَتَيْنِ بَعْدَ الْعَصْرِ عِنْدِي قَطُّ ‏.‏

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also referenced under: Book 6, Hadith 581 (In-Book)