لَّقَدْ كَفَرَ ٱلَّذِينَ قَالُوٓا۟ إِنَّ ٱللَّهَ ثَالِثُ ثَلَٰثَةٍ ۘ وَمَا مِنْ إِلَٰهٍ إِلَّآ إِلَٰهٌ وَٰحِدٌ ۚ وَإِن لَّمْ يَنتَهُوا۟ عَمَّا يَقُولُونَ لَيَمَسَّنَّ ٱلَّذِينَ كَفَرُوا۟ مِنْهُمْ عَذَابٌ أَلِيمٌ

Certainly they disbelieve who say: Surely Allah is the third (person) of the three; and there is no god but the one Allah, and if they desist not from what they say, a painful chastisement shall befall those among them who disbelieve.