The Book of Qiyam Al-Lail (The Night Prayer) and Voluntary Prayers During the Day
20/18. Chapter:
What is done when one begins the prayer standing and mentioning the differences with those who reported from 'Aisha concerning it
Sunan an-Nasai
أَخْبَرَنَا عَبْدَةُ بْنُ عَبْدِ الرَّحِيمِ، قَالَ أَنْبَأَنَا وَكِيعٌ، قَالَ حَدَّثَنِي يَزِيدُ بْنُ إِبْرَاهِيمَ، عَنِ ابْنِ سِيرِينَ، عَنْ عَبْدِ اللَّهِ بْنِ شَقِيقٍ، عَنْ عَائِشَةَ، قَالَتْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يُصَلِّي قَائِمًا وَقَاعِدًا فَإِذَا افْتَتَحَ الصَّلاَةَ قَائِمًا رَكَعَ قَائِمًا وَإِذَا افْتَتَحَ الصَّلاَةَ قَاعِدًا رَكَعَ قَاعِدًا .
It was narrated hat Aishah said: "The Messenger of Allah (ﷺ) used to pray standing and sitting. If he started to pray standing, he would bow standing and if he started to pray sitting, he would bow sitting."
Reference : Sunan an-Nasa'i 1647In-book reference : Book 20, Hadith 50English translation : Vol. 2, Book 20, Hadith 1648