The Messenger of Allah ﷺ used to pray for long stretches at night. When he prayed standing, he would bow from a standing position, and when he prayed sitting, he would bow from a sitting position.
أخبرنا قتيبة قال حدثنا حماد عن بديل وأيوب عن عبد الله بن شقيق
كان رسول الله ﷺ يصلي ليلا طويلا فإذا صلى قائما ركع قائما وإذا صلى قاعدا ركع قاعدا
Muslim reported it in the Book of the Travelers' Prayer, chapter on the permissibility of performing voluntary prayer standing or sitting, hadith 106/730, from Qutayba, with this wording. It is also in Kubra, hadith 1355.