Surah Al-Ma'idah, ayah 73

لَّقَدۡ كَفَرَ ٱلَّذِينَ قَالُوٓاْ إِنَّ ٱللَّهَ ثَالِثُ ثَلَٰثَةٖۘ وَمَا مِنۡ إِلَٰهٍ إِلَّآ إِلَٰهٞ وَٰحِدٞۚ وَإِن لَّمۡ يَنتَهُواْ عَمَّا يَقُولُونَ لَيَمَسَّنَّ ٱلَّذِينَ كَفَرُواْ مِنۡهُمۡ عَذَابٌ أَلِيمٌ ٧٣

Llaqad kafaral-ladhīna qālū innallāha thālithu thalāthatin wamā min ilāhin illā ilāhun wāhidun wa il lam yantahū 'ammā yaqūlūna layamassannal-ladhīna kafarū minhum 'adhābun alīm

They have certainly disbelieved who say, "Allāh is the third of three."²⁷⁶ And there is no god except one God. And if they do not desist from what they are saying, there will surely afflict the disbelievers among them a painful punishment.