Musnad Ahmad 1007:73

'Abd al-Razzaq narrated to us, Ibn Jurayj informed us, 'Amir ibn 'Abd Allah ibn al-Zubayr informed me, from 'Amr ibn Sulaym al-Zuraqi, that he heard Abu Qatadah say: "The Prophet, peace and blessings of Allah be upon him, prayed while Umamah, the daughter of Zaynab, the daughter of the Prophet, peace and blessings of Allah be upon him—and she was the daughter of Abu al-'As ibn al-Rabi' ibn 'Abd al-'Uzza—was upon his neck. When he bowed, he would place her down, and when he rose from his prostration, he would take her and return her to his neck." 'Amir said: "I did not ask him which prayer it was." Ibn Jurayj said: "And it was narrated to me from Zayd ibn Abi 'Attab, from 'Amr ibn Sulaym, that it was the morning prayer." Abu 'Abd al-Rahman said: "He authenticated it."