“The Prophet ﷺ used to recite Qur’an sitting down, then when he wanted to bow he would stand up for as long as it takes a person to recite forty Verses.”
كَانَ النَّبِيُّ ﷺ يَقْرَأُ وَهُوَ قَاعِدٌ فَإِذَا أَرَادَ أَنْ يَرْكَعَ قَامَ قَدْرَ مَا يَقْرَأُ إِنْسَانٌ أَرْبَعِينَ آيَةً