Musnad Abu Ya'la al-Mawsili 115:226

Ubayd Allah narrated to us, Yahya ibn Sa'id narrated to us, from Sa'id ibn Abi 'Aruba, from Qatada, from Anas ibn Malik: That the Messenger of Allah (peace be upon him) would not raise his hands in any supplication except in the prayer for rain (Istisqa'), for indeed he would raise them until his armpits became visible.