Your friend (Job) is suffering. What do you do? First, what you don't do.
Watch the comparisons, "It's not as bad as that time I...," or "My brother-in-law had the same thing." And don't lay the blame, "Well, you had it coming...," or "You just need more faith." Be careful trying to explain God, "This is God making you strong." You're not the doctor, so don't tell them, "I read on the internet about a special treatment." Beware "At least." You know, "At least you've had a good life." And, oh, those clichés and platitudes! "Look on the bright side." "What doesn't kill you makes you stronger."
We fear the silence, so we fill the silence. Awkwardly. "If only you would be altogether silent! For you, that would be wisdom" (Job 13:5).
If these are the don't's, what do we do when our friend is suffering? First, show up: Job's friends got it right for a week (Job 2:13). Just be there. Then love them; talk relationally. And serve them; see a need and meet it. And pray; bring God with you.
Father God, you are my comfort and my refuge. You are all-powerful and all-knowing. There is nothing so big that I cannot bring it to you. You are an intimate, loving Father. There is nothing so small that you are not interested. You delight in my prayers, which is amazing and wonderful.
God, may I walk through my days with you, speaking to you always, sharing my pleasures and my pains, my desires and my concerns. Then, God, may I find peace and contentment, because I do not walk alone.