Musnad Ahmad 1153:404

Al-Khuza'i narrated to us, he said: Layth informed us, from Yazid ibn al-Had, from Musa ibn Sarjas, from al-Qasim ibn Muhammad, from Aisha, who said: I saw the Messenger of Allah, may Allah bless him and grant him peace, while he was dying, and beside him was a cup containing water. He would insert his hand into it, then wipe his face with it, and say: "O Allah, assist me against the agonies of death."