"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." (Using translation from Nasāʾī 1647)
كَانَ رَسُولُ اللهِ ﷺ يُصَلِّي قَائِمًا وَقَاعِدًا فَإِذَا افْتَتَحَ الصَّلَاةَ قَائِمًا رَكَعَ قَائِمًا وَإِذَا افْتَتَحَ الصَّلَاةَ قَاعِدًا رَكَعَ قَاعِدًا