Is expiation obligatory upon a mother who caused the death of her young daughter by scalding her with boiling water that she had left boiling?

The ruling regarding the death of a child by drowning in a pot of water depends on whether there was negligence or not. If placing the water on the ground without a cover, or allowing the child to play close to it in a place where she commonly enters, is considered negligence, then the mother is obligated to offer expiation (freeing a believing slave or fasting for two consecutive months) because she was a cause of the killing. However, if placing the water was customary and there was no negligence, then nothing is required of the mother.