He vowed to fast for a month; can he fast thirty days separately?
Question

                I vowed to fast for a month for Allaah, but I did not specify which month. Is it acceptable for me to fast thirty days separately or not?.
Praise be to Allah.
    If a person vows to fast for a month but speaks in general 
    terms, the fuqaha’ say that he has the choice between either fasting for a 
    month based on sighting of the new moon, in which case it must be 
    consecutive days, and it is acceptable if the month turns out to be 
    twenty-nine days, because this is still called a month; or of fasting for a 
    number of days that is not connected to the lunar month, in which case he 
    has to fast for thirty days, because if he fasts on the basis of the number 
    of days it has to be thirty, and it is permissible for him to fast them 
    separately. 

    So he has the choice between fasting for a lunar month, in 
    which case it is the month that counts, but it is also permissible for him 
    to fast the number of days, in which case he must fast for thirty days, 
    whether they are separate or consecutive.