It is narrated from Sayyiduna Ali (may Allah be pleased with him) that the Prophet (peace and blessings of Allah be upon him) used to offer the two Sunnah rak'ahs of Fajr close to the time of Iqamah.
Hadith Referenceمسند احمد / مسند الخلفاء الراشدين / 569
Hadith Gradingحکم دارالسلام:إسناده ضعيف، لضعف الحارث، وهو ابن عبدالله الأعور