Musnad Ahmad 1153:1886

Abu Kamil narrated to us, he said: Hammad narrated to us, Budayl ibn Maysarah narrated to us, from Abdullah ibn Shaqiq, from Aisha, she said: "When the Messenger of Allah (peace and blessings of Allah be upon him) recited while standing, he would bow while standing, and when he recited while sitting, he would bow while sitting."