Divorce from a husband who is addicted to smoking
Question

                My husband is addicted to smoking and he suffers from asthma. There have been many problems between us concerning his giving up smoking. Five months ago my husband prayed two rak’ahs to Allaah and swore that he would never smoke again, but he started smoking again one week after making that vow, and the problems between us started again. I asked him for a divorce but he promised me that he would not start smoking again and that he would give it up forever, but I am not confident that he will be able to keep his word. What is your opinion, what is the expiation for his broken vow and what do you advise me to do?
Praise be to Allah.
    Smoking is one of the evil things that are forbidden, and it 
    causes a great deal of harm. Allaah says in His Holy Book, in Soorat 
    al-Maa’idah (interpretation of the meaning): 
“They ask you (O 
    Muhammad) what is lawful for them (as food ). Say: ‘Lawful unto you are 
    At‑Tayyibaat [all kinds of Halaal (lawful‑good) foods which Allaah has made 
    lawful (meat of slaughtered eatable animals, milk products, fats, vegetables 
    and fruits)]’” [al-Maa'idah 5:4]

     And He says in Soorat al-A’raaf, describing the Prophet 
    Muhammad  (peace and blessings of Allaah be upon him):

     “he allows them as lawful At‑Tayyibaat (i.e. all good and 
    lawful as regards things, deeds, beliefs, persons and foods), and prohibits 
    them as unlawful Al‑Khabaa’ith (i.e. all evil and unlawful as regards 
    things, deeds, beliefs, persons and foods)”
[al-A’raaf 5:157] 

    Undoubtedly smoking is an evil and unlawful thing, so your 
    husband must give it up and keep away from it, in obedience to Allaah and 
    His Messenger  (peace and blessings of Allaah be upon him) and so as to 
    avoid that which incurs the wrath of Allaah, and to protect his religious 
    commitment and health, and to maintain good relations with you.  As 
    expiation for his broken oath he must offer kafaarat yameen, as well as 
    repenting to Allaah for starting to smoke again. This expiation means 
    feeding or clothing ten poor persons, or freeing a believing slave; it is 
    sufficient to give them dinner or lunch, or to give each of them half a saa’ 
    of the staple food of the country Which is equivalent to a kilo and a half.
    

    We advise you not to ask him for a divorce if he prays and he 
    is a man of good conduct, and if he gives up smoking. But if he persists in 
    this sin there is nothing to prevent you from asking him for a divorce.