Verš 68:2

díky milosti Pána svého ty blázen žádný nejsi!

Tafsir al-Jalalayn

You are not, O Muhammad (s), by the grace of your Lord, a madman, that is to say, madness is precluded in your case, on account of your Lord’s grace to you by way of [His assigning to you] prophethood and in other ways — this was a refutation of their saying that he was a madman.