Uthman bin Abu As reported,
He complained to the Messenger of Allah ﷺ about a pain he had been feeling in his body ever since he became Muslim. The Messenger of Allah ﷺ said to him, "Place your hand on the part of your body that hurts and say, 'In the name of Allah,' three times, then say seven times, 'I seek refuge in Allah and His power from the evil of what I find and fear.'"
Muslim 5737
Difficultحدثني أبو الطاهر وحرملة بن يحيى قالا أخبرنا ابن وهب أخبرني يونس عن ابن شهاب أخبرني نافع بن جبير بن مطعم
عن عثمان بن أبي العاص الثقفي
أنه شكا إلى رسول الله ﷺ وجعا يجده في جسده منذ أسلم فقال له رسول الله ﷺ ضع يدك على الذي تألم من جسدك وقل باسم الله ثلاثا وقل سبع مرات أعوذ بالله وقدرته من شر ما أجد وأحاذر
Muslim narrated the hadith of Ibn Wahb, from Yunus, from Zuhri, from Nafi bin Jubayr, from Uthman bin Abu As, "I complained to the Prophet 
of a pain I was feeling."He said, Uthman bin Hakam narrated it from Yunus, from Zuhri, from Nafi bin Jubayr, that the Prophet, may Allah bless him and his family and grant him peace, said to Uthman, transmitting it as a mursal report.