Musnad Ahmad 1007:47

Yunus narrated to us, Aban narrated to us, from Yahya ibn Abi Kathir, from Abdullah ibn Abi Qatadah, from his father, who said: The Messenger of Allah (peace and blessings of Allah be upon him) used to lead us in prayer, and he would recite in the first two rak'ahs of the Dhuhr and Asr prayers the Opening of the Book (Al-Fatihah) and two surahs. He would sometimes let us hear the verse. He would recite in the last two rak'ahs the Opening of the Book. He used to lengthen the first rak'ah of the Fajr prayer and the first rak'ah of the Dhuhr prayer.