Sunan an-Nasa'i, Book 13, Hadith 179 (In-Book)

It was narrated that Jabir bin Samurah said: "When the Messenger of Allah prayed fajr, he would sit in the place where he had prayed until the sun rose."

أَخْبَرَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا أَبُو الأَحْوَصِ، عَنْ سِمَاكٍ، عَنْ جَابِرِ بْنِ سَمُرَةَ، قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم إِذَا صَلَّى الْفَجْرَ قَعَدَ فِي مُصَلاَّهُ حَتَّى تَطْلُعَ الشَّمْسُ ‏.‏

sunnah.com