You say that your brother was hungry, thirsty, and so on when he was sick, and he blasphemed. You also said that your brother was committing a mortal sin.
God, though, Who is very compassionate, wanted to bring him to a realization of his guilt so that he would repent, so He gave him this illness out of paternal love as a spiritual medication to cure his soul of its illness. If you had looked after your brother and offered him every bodily comfort, what pains would he have suffered for God to see and have pity on him? You should realize that the more he was tormented, the more his penalty was lightened! God gave him the illness and allowed the brethren to neglect their duty towards him so that his conscience would make him feel remorse and repent. He is like a patient who is given medicine by a doctor, but lacks the necessary patience. Thus, he curses and grumbles at the doctor, which only leads to his own demise.
Elder Ephraim of Arizona