Surat Al Isra' (47-48)

{نَّحْنُ أَعْلَمُ بِمَا يَسْتَمِعُونَ بِهِ إِذْ يَسْتَمِعُونَ إِلَيْكَ وَإِذْ هُمْ نَجْوَى إِذْ يَقُولُ الظَّالِمُونَ إِن تَتَّبِعُونَ إِلاَّ رَجُلاً مَّسْحُوراً} (الإسراء: 47)

47- We know the secret talks of polytheists chiefs when they listen to you recitation secretly. Their chiefs who wronged themselves as well as their people said: If you follow Muhammad, you will follow a man touched by sorcery, and he is mad.

{انظُرْ كَيْفَ ضَرَبُواْ لَكَ الأَمْثَالَ فَضَلُّواْ فَلاَ يَسْتَطِيعْونَ سَبِيلاً} (الإسراء: 48)

48- O Prophet, look how did they described you and claimed that you are bewitched, and some said you were a priest, whereas others said you were a poet. They prevented their natural disposition from hearing the truth and uttered disbelief, so they strayed and could not follow the way of guidance nor did they justified their attitude with a useful speech or a convincing plea.