Musnad Ahmad 1007:129

Yahya ibn Sa'id narrated to us, from Ibn 'Ajlan, Sa'id and 'Amir ibn 'Abd Allah ibn al-Zubayr narrated to me, from 'Amr ibn Sulaym, from Abu Qatadah, that the Prophet, peace and blessings of Allah be upon him, used to come out while carrying the daughter of Zaynab on his neck, and he would lead the people in prayer. When he bowed, he would put her down, and when he stood up, he would carry her.