Musannaf Ibn Abi Shayba 18:1151

Abu Bakr narrated to us, he said: Ibn Mushir narrated to us, from Sa’id, from Qatadah, from Khallas, who said: A man hired four men to dig a well for him. They dug it, and the well collapsed upon them, and one of them died. This was raised to Ali, and he held the three [surviving men] liable for three-quarters of the blood money, and he remitted from them one-quarter of the blood money.