Muwatta Imam Malik Book of Prayer in Congregation, Hadith 27

Yahya related to me from Malik from Zayd ibn Aslam that Amr ibn Rafi said, "I was writing a Qur'an for Hafsa, umm al-muminin, and she said, 'When you reach this ayat, let me know, "Guard the prayers carefully and the middle prayer and stand obedient to Allah." When I reached it I told her and she dictated to me, 'Guard the prayers carefully and the middle prayer and the asr prayer and stand obedient to Allah.' "

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ زَيْدِ بْنِ أَسْلَمَ، عَنْ عَمْرِو بْنِ رَافِعٍ، أَنَّهُ قَالَ كُنْتُ أَكْتُبُ مُصْحَفًا لِحَفْصَةَ أُمِّ الْمُؤْمِنِينَ فَقَالَتْ إِذَا بَلَغْتَ هَذِهِ الآيَةَ فَآذِنِّي {حَافِظُوا عَلَى الصَّلَوَاتِ وَالصَّلاَةِ الْوُسْطَى وَقُومُوا لِلَّهِ قَانِتِينَ } فَلَمَّا بَلَغْتُهَا آذَنْتُهَا فَأَمْلَتْ عَلَىَّ حَافِظُوا عَلَى الصَّلَوَاتِ وَالصَّلاَةِ الْوُسْطَى وَصَلاَةِ الْعَصْرِ وَقُومُوا لِلَّهِ قَانِتِينَ .