Sayyidah Aisha (may Allah be pleased with her) narrates that the Messenger of Allah (peace and blessings be upon him) used to perform four units of Sunnah prayer before Zuhr, and two units before the Asr prayer, and he never omitted them. She also states that the Prophet (peace and blessings be upon him) used to say: "The best surahs that are recited in the two units before Fajr are « قُلْهُوَاللَّهُأَحَدٌ » and « قُلْيَاأَيُّهَاالْكَافِرُونَ »."
Hadith Referenceصحيح ابن خزيمه / جماع أبواب الركعتين قبل الفجر وما فيها من السنن / 1114