Amr bin Shu'ayb narrates from his father, and he from his grandfather (may Allah be pleased with him), that the Prophet (peace and blessings be upon him) said: "The testimony of a treacherous man or woman, of a man or woman upon whom a prescribed punishment (hadd) has been carried out in Islam, and of one who harbours rancour against his brother, will not be accepted."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 20568