Musnad Ahmad 626:40

'Abd al-Razzaq narrated to us, Sufyan informed us, from Ibn Abi Layla, from al-Sha'bi, from al-Mughira ibn Shu'ba: "He stood up during the first two rak'ahs, so they glorified Allah (said 'SubhanAllah') to him, but he did not sit. When he finished his prayer, he performed two prostrations after the taslim." Then he said: "This is how the Messenger of Allah, peace and blessings of Allah be upon him, did."