Musannaf Ibn Abi Shayba 18:1195

Abu Bakr narrated to us, he said: Muhammad ibn Yazid narrated to us, from Ayyub Abu al-Ala, who said: Abu Hashim said regarding four people who testified against a man for adultery, then one of them retracted: Upon him is a quarter of the blood money (diyah). And Ibn Sirin said: If he says, "I erred and intended someone else," then upon him is the full blood money. And if he says, "I intended to kill him," he is killed for it.