Musnad Ahmad 1153:2170

Hammad ibn Khalid narrated to us, he said: Malik narrated to us, from al-Zuhri, from Urwah, from Aisha, "That the Prophet, peace and blessings of Allah be upon him, when he was ill, would recite the Mu'awwidhatayn (the two surahs of seeking refuge) over himself and blow." Aisha said: "Then when he became heavy [with illness], I began to blow upon him with them, and I would wipe with his right hand, seeking its blessing."