In Sahih Muslim it is related from Ibn ʿAbbās:

“Dimād came to Mecca—he was a man of Azd Shanūʿah—and he used to treat people afflicted by this ‘wind’ through ruqyah (healing incantations). He overheard some foolish men among the people of Mecca saying, ‘Muhammad is mad.’ So he said, ‘If I could only meet this man, perhaps Allah would heal him through me.’

He continued: I met Muhammad and said, ‘I perform ruqyah for this affliction, and Allah cures through my hands whom He wills. So come to me.’

Muhammad replied:

‘All praise belongs to Allah; we praise Him and seek His help. Whomever Allah guides, none can mislead, and whomever He leaves astray, none can guide. I bear witness that there is no deity except Allah alone, without partner, and that Muhammad is His servant and Messenger. To proceed…’

Dimād said, ‘Repeat those words of yours for me.’ The Messenger of Allah, peace and blessings be upon him, repeated them for him three times. Dimād then declared, ‘By Allah, I have heard the speech of soothsayers, the speech of sorcerers, and the speech of poets, yet I have never heard anything like these words of yours. Indeed, they have reached the very depths of the sea.’”