The Prophet ﷺ used to remain seated in his place of prayer after performing the dawn prayer until the sun rose Hasna.
حدثنا وكيع حدثنا سفيان عن سماك بن حرب
أن النبي ﷺ كان يجلس في مصلاه إذا صلى الغداة حتى تطلع الشمس حسناء
Its chain of transmission is sahih, it was mentioned previously at 20865.