Quran 8:35 from Surah Al-Anfaal on Divine Marvels.
وَمَا كَانَ صَلَاتُهُمۡ عِندَ ٱلۡبَيۡتِ إِلَّا مُكَآءٗ وَتَصۡدِيَةٗۚ فَذُوقُواْ ٱلۡعَذَابَ بِمَا كُنتُمۡ تَكۡفُرُونَ
English translation: And not was their prayer at the House except whistling and clapping So taste the punishment because you used to disbelieve
Transliteration: wama kana salatuhum inda al-bayti illa mukaan watasdiyatan fadhuqu al-'adhaba bima kuntum takfuruna