Musnad Ahmad 1007:4

Isma'il ibn Ibrahim narrated to us, Hisham al-Dastawa'i narrated to us, Yahya ibn Abi Kathir narrated to us, 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, reciting for us in the first two rak'ahs of the Dhuhr prayer, and he would let us hear the verse sometimes. He would make the first (rak'ah) long and the second short. He used to do that in the Subh (morning) prayer, making the first long and the second short. And he used to recite for us in the first two rak'ahs of the 'Asr prayer.