Is blood money obligatory for someone who left the door of his tractor open with its keys inside, which led to a child starting it and killing another child?

If a man leaves a vessel and a child plays with it, causing the death of another, then the blood money (Diyah) is obligatory upon the 'Aqilah (male relatives on the father's side) of the child who caused it. This is because the ruling is attributed to the direct actor, which is what the jurists have stipulated: that liability falls upon the direct actor, not the one who merely caused the action.

Furthermore, whoever performs a permissible act is not liable for any resulting harm. Expiation (Kaffarah) is obligatory from the property of the killing child.