Sayyiduna Abdullah bin Amr (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "No other prayer is to be performed before (the obligatory prayer of) Fajr; only the two rak'ahs (sunnah) of Fajr are to be performed."
Al-Bazzar and al-Tabarani in al-Mu'jam al-Kabir recorded it; its chain contains Abd al-Rahman bin Ziyad bin An'um, about whose use as evidence there is disagreement.