Musnad Ahmad 1007:16

Sufyan narrated to us, from Uthman ibn Abi Sulayman and Ibn Ajlan, from Amir ibn Abdullah ibn al-Zubayr, from Amr ibn Sulaym, from Abu Qatadah, who said: I saw the Messenger of Allah (peace and blessings of Allah be upon him) leading the people in prayer, while Umamah bint Abi al-As—meaning he was carrying her—was with him. When he bowed, he would put her down, and when he finished the prostration, he would pick her up.