﴿ 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 ‘Lord appoint for me some sign’ namely some indication of my wife’s becoming pregnant. Said He ‘Your sign for this is that you shall not speak to people that is that you should refrain from speaking to them but not from speaking the remembrance of God exalted be He for three nights that is together with the days thereof as stated in sūrat Āl ‘Imrān ‘for three days’ Q. 341 while you are in sound health’ sawiyyan a circumstantial qualifier referring to the subject of the verb tukallima ‘you shall not speak’ in other words despite there being no defect in you.