Musnad Ahmad 1153:1158

Hashim narrated to us, Layth narrated to us, from Yazid ibn Abdullah ibn Usamah, from Musa ibn Sarjas, from al-Qasim ibn Muhammad, from Aisha, that she said: I saw the Messenger of Allah, may Allah bless him and grant him peace, while he was dying, and there was a cup with water in it beside him. He would put his hand into the cup and wipe his face with the water, while saying: "O Allah, help me against the agonies of death."