"The Messenger of Allah ﷺ used to recite sitting, and when he wanted to bow he would stand up for as long as it takes a person to recite forty verses." (Using translation from Nasāʾī 1650)
كَانَ رَسُولُ اللهِ ﷺ يَقْرَأُ وَهُوَ قَاعِدٌ فَإِذَا أَرَادَ أَنْ يَرْكَعَ قَامَ قَدْرَ مَا يَقْرَأُ إِنْسَانٌ أَرْبَعِينَ آيَةً