Full Sharh — Riyad as-Salihin 226
وعن أبي عبد الله عثمان بن أبي العاص رضي الله عنه أنه شكي إلي رسول الله صلى الله عليه وسلم وجعاً يجده في جسده فقال رسول الله صلى الله عليه وسلم "ضع يدك علي الذي تألم من جسدك وقل: بسم الله -ثلاثاً- وقل سبع مرات: أعوذ بعزة الله وقدرته من شر ما أجد وأحاذر” ((رواه مسلم)).
English Translation
Abu 'Abdullah bin Abul-'as (May Allah be pleased with him) reported:: I complained to the Messenger of Allah (ﷺ) about a pain I had in my body. The Messenger of Allah (ﷺ) said, "Place your hand where you feel pain and say: 'Bismillah (With the Name of Allah)' three times; and then repeat seven times: 'A'udhu bi'izzatillahi wa qudratihi min sharri ma ajidu wa 'uhadhiru (I seek refuge with Allah and with His Power from the evil that afflicts me and that which I apprehend)."'.
Source
Riyad as-Salihin(رياض الصالحين)
The Book of Visiting the Sick
Hadith Number
226