Al-Ma'idah 5:73

Laqad kafara allatheena qalooinna Allaha thalithu thalathatin wamamin ilahin illa ilahun wahidun wa-inlam yantahoo AAamma yaqooloona layamassanna allatheenakafaroo minhum AAathabun aleem

They have certainly disbelieved who say, "Allāh is the third of three." 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.

Surely, disbelievers are those who say, “Allah is the third of the three” while there is no god but One God. If they do not desist from what they say, a painful punishment shall certainly befall such disbelievers.