It is narrated from Sayyiduna Jabir bin Samurah (may Allah be pleased with him) that when the Messenger of Allah (peace and blessings be upon him) prayed the Fajr prayer, he would remain sitting in his place of prayer until the sun rose.
Imam Muslim (may Allah have mercy on him) mentioned this narration in his Sahih, and in it is this addition: 'hatta tatlu'ash-shamsu hasanan' (until the sun had fully risen).
Abu Khaythamah (may Allah have mercy on him) narrated this report from Simak, and in it he said only: 'fa idha tala'at qama' (when it rose, he stood up); in place of 'hasanan' there is the word 'qama'.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3021