﴿ قَالَ رَبِّ ٱجْعَل لِّىٓ ءَايَةًۭ ۚ قَالَ ءَايَتُكَ أَلَّا تُكَلِّمَ ٱلنَّاسَ ثَلَٰثَ لَيَالٍۢ سَوِيًّۭا ﴾

“[Zachariah] prayed: "O my Sustainer! Appoint a sign for me!" Said [the angel]: "Thy sign shall be that for full three nights [and days] thou wilt not speak unto men.”

(He said: My Lord!) O my Lord! (Appoint for me some token) some sign when my wife becomes pregnant. (He said: Thy token is that thou, with no bodily defect, shall not speak unto mankind) will not be able to speak to people (three nights) without suffering dumbness or any other illness.