Al-Adab Al-Mufrad — Hadith #46950

Sa`id bin Dawud told us: Malik told us that Nafi` told him that `Abdullah bin `Umar told him that the Messenger of Allah, may God bless him and grant him peace, said: “If one says to another: ‘You are an unbeliever,’ then one of them has committed disbelief. If the one to whom he said it is an unbeliever, then he has spoken the truth. But if he is not as he said it to him, then the one to whom he said it has committed disbelief.”