قَالَ رَبِّ ٱجْعَل لِّىٓ ءَايَةً ۚ قَالَ ءَايَتُكَ أَلَّا تُكَلِّمَ ٱلنَّاسَ ثَلَٰثَ لَيَالٍ سَوِيًّا

He said: My Lord! give me a sign. He said: Your sign is that you will not be able to speak to the people three nights while in sound health.