Authentic Supplication Number 149.

It is reported by her that the Prophet  used to invoke the protection of Allah upon some of his family, while passing his right hand [over the place of ailment] and saying: ‘Allahumma rabban-nasi, ‘athhibil-basa, washfi ‘antash-shafee, la shifa’a ‘illa shifa’uka, shifa’an la yughadiru saqaman (168).

(168) O’ my ‘ilah Lord of the people, remove the trouble, and heal for You are the Healer, No healing is of any avail but yours; a healing that will leave behind no ailment.

Agreed upon by Bukhari and Muslim. Al-Albani included this hadeeth in The Authentic of Good Sayings as #120.