:Hawzah News Agency – The merciful prophet of Islam says:

مَن أمَّنَ رَجُلاً على‏ دَمِهِ فقَتلَهُ فأنا بَري‏ءٌ مِن القاتل، و إنْ كانَ المَقتولُ كافراً.

'When a man assures another of sparing his life and then kills him, [know that] I renounce the killer, even if the victim is an unbeliever.'

Source: Kanz al-Ummal, no. 10930