Surah Aali Imran (The Family of Imran), Verse 41

قَالَ رَبِّ اجْعَلْ لِّیْۤ اٰیَةً قَالَ اٰیَتُكَ اَلَّا تُكَلِّمَ النَّاسَ ثَلٰثَةَ اَیَّامٍ اِلَّا رَمْزًا وَاذْكُرْ رَّبَّكَ كَثِیْرًا وَّسَبِّحْ بِالْعَشِیِّ وَالْاِبْكَارِ 

Qaala Rabbij 'al leee Aayatan qaala Aaayatuka allaa tukalliman naasa salaasata ayyaamin illa ramzaa; wazkur Rabbaka kaseeranw wa sabbih bil'ashiyyi wal ibkaar

“He said: "O my Lord! Give me a Sign!" "Thy Sign," was the answer, "Shall be that thou shalt speak to no man for three days but with signals. Then celebrate the praises of thy Lord again and again, and glorify Him in the evening and in the morning."”

Quran 3:41 (Yusuf Ali Translation)