Word by Word Analysis

وَمَا كَانَ صَلَاتُهُمْ عِندَ ٱلْبَيْتِ إِلَّا مُكَآءً وَتَصْدِيَةً ۚ فَذُوقُوا۟ ٱلْعَذَابَ بِمَا كُنتُمْ تَكْفُرُونَ 35

And their prayer at the House [i.e., the Kaʿbah] was not except whistling and handclapping. So taste the punishment for what you disbelieved [i.e., practiced of deviations].