﴿ مَآ أَنتَ بِنِعْمَةِ رَبِّكَ بِمَجْنُونٍۢ ﴾

“Thou art not, by thy Sustainer's grace, a madman!”

(Thou art not) O Muhammad, (for your Lord's favour) for the prophethood and Islam bestowed (unto thee, a madman) bewitched. This is the reason why Allah made the above oath.