Musnad Ahmad 1007:79

Makhlad ibn Yazid al-Harrani narrated to us, al-Awza’i narrated to us, from Yahya—meaning Ibn Abi Kathir—from ‘Abdullah ibn Abi Qatadah, from his father, Abu Qatadah, the horseman of the Messenger of Allah (may Allah bless him and grant him peace), from the Prophet (may Allah bless him and grant him peace): "He used to recite in the first two rak'ahs of the Dhuhr and the ‘Asr [prayers] the Opening of the Book (Al-Fatihah) and a surah, and in the last two rak'ahs the Opening of the Book (Al-Fatihah)."