Going to his second wife, who lives with his mother, on a day that is not hers
Question

                A person has two wives; one of them stays with his ill mother to look after her. Is it permissible for the husband to visit his mother to see how she is for little while, and then goes to his other wife (who has the right of the day)?.
Praise be to Allah.
    It is permissible for the husband to go to his second wife 
    during the day if that is for a reason, such as checking on her, or giving 
    her her maintenance or taking something from the house and so on. 

    He may also be intimate with her however he wishes, without 
    having intercourse, but he does not have the right to spend a lot of time 
    with her. 

    But if that is at night, then it is not permissible for him 
    to go to her unless it is necessary, such as if she is very ill, or there is 
    a fire and so on. 

    This has been discussed in the answer to question no.
    106513. 

    But it seems that you are going there to visit your sick 
    mother, and asking about her is permissible by night or by day, so long as 
    your intention is to visit your mother, and not to visit your wife. 

    In this case your visits should only be as long as necessary, 
    and when you have achieved your purpose of checking on your mother, taking 
    care of her, helping her with what she needs and comforting her, then you 
    should leave and go to your other wife, and you should not stay with your 
    mother for a long time when there is no need for that. 

    And Allaah knows best.