Muwatta Imam Malik Book of Prayer in Congregation, Hadith 24

Yahya related to me from Malik from Abdullah ibn Yazid al-Madani and from Abu'n Nadr from Abu Salama ibn Abd ar-Rahman from A'isha, the wife of the Prophet ﷺ that the Messenger of Allah ﷺ used to pray sitting. He would recite sitting, and then, when about thirty or forty ayats of what he was reciting remained, he would stand up and recite standing and then go into ruku and sajda. He would do the same in the second raka.

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ عَبْدِ اللَّهِ بْنِ يَزِيدَ الْمَدَنِيِّ، وَعَنْ أَبِي النَّضْرِ، عَنْ أَبِي سَلَمَةَ بْنِ عَبْدِ الرَّحْمَنِ، عَنْ عَائِشَةَ، زَوْجِ النَّبِيِّ ﷺ أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ يُصَلِّي جَالِسًا فَيَقْرَأُ وَهُوَ جَالِسٌ فَإِذَا بَقِيَ مِنْ قِرَاءَتِهِ قَدْرُ مَا يَكُونُ ثَلاَثِينَ أَوْ أَرْبَعِينَ آيَةً قَامَ فَقَرَأَ وَهُوَ قَائِمٌ ثُمَّ رَكَعَ وَسَجَدَ ثُمَّ صَنَعَ فِي الرَّكْعَةِ الثَّانِيَةِ مِثْلَ ذَلِكَ .