أَخْبَرَنَا قُتَيْبَةُ، عَنْ مَالِكٍ، عَنْ زَيْدِ بْنِ أَسْلَمَ، عَنِ الْقَعْقَاعِ بْنِ حَكِيمٍ، عَنْ أَبِي يُونُسَ، مَوْلَى عَائِشَةَ زَوْجِ النَّبِيِّ صلى الله عليه وسلم قَالَ أَمَرَتْنِي عَائِشَةُ أَنْ أَكْتُبَ لَهَا مُصْحَفًا فَقَالَتْ إِذَا بَلَغْتَ هَذِهِ الآيَةَ فَآذِنِّي ‏{‏ حَافِظُوا عَلَى الصَّلَوَاتِ وَالصَّلاَةِ الْوُسْطَى ‏}‏ فَلَمَّا بَلَغْتُهَا آذَنْتُهَا فَأَمْلَتْ عَلَىَّ حَافِظُوا عَلَى الصَّلَوَاتِ وَالصَّلاَةِ الْوُسْطَى وَصَلاَةِ الْعَصْرِ وَقُومُوا لِلَّهِ قَانِتِينَ ‏.‏ ثُمَّ قَالَتْ سَمِعْتُهَا مِنْ رَسُولِ اللَّهِ صلى الله عليه وسلم ‏.‏

It was narrated that Abu Yunus, the freed slave of 'Aishah the wife of the Prophet (PBUH), said: "Aishah told me to copy a Mushaf for her, and she said: 'When you reach this verse, call my attention: Guard strictly the Salawat especially the middle (Al-Wusta) Salah. [1] When I reached it, I called her attention and she dictated to me: 'Guard strictly the Salawat expecially the middle (Al-Wusta) Salah and the 'Asr prayer, and stand before Allah with obedience.' Then she said: 'I heard it from the Messenger of Allah (PBUH).'" [1] Al-Baqarah 2:238. Translation Not Available

Book Ref: Sunan An Nisai Book 5 Hadith 472
Web Ref:  Sunan An Nisai Vol 1 Book 5 Hadith 473