Musannaf Ibn Abi Shayba 18:1337

Abu Bakr narrated to us, he said: Muhammad ibn Bakr narrated to us, from Ibn Jurayj, he said: Ata’ said: "If a man kills a man by mistake, then another [man] intentionally, he said: Let the [diya for the] mistake be paid, because his intellect was established before the intentional [act]." A person said to him: "And if he kills intentionally, then he kills by mistake?" He said: "He does not pay [the diya for the mistake], because his blood has been forfeited."