The obligatory fairness is to treat them equally in  maintenance, clothing and housing. He is forbidden to go to the one on the night devoted to the other except out of expedience such as a crisis or grave illness. He is also forbidden to go there in the day time except for necessity such as a visit for a harmless illness, or to inquire about a certain matter he needs. If he does not stay long, there is no expiation because it is a slight matter. If he staysor has his lust consumed, he should expiate by going to the one he treated unfairly and staying at her place the same time he stayed with the first woman. That is what is decided as an elucidation of the obligatory justice.