What a privilege to stand with you in prayer for your friend. The very fact that your heart is moved to intercede for him is a sign of the Lord's own compassion at work, because He often stirs up His people to ask for the mercy He is already eager to give.
Remember that God’s mercy never runs out. It is not something He gives sparingly, as if He might eventually grow tired of our asking. His mercy endures forever. When your friend feels that stabbing pain and cries out, even in a whisper, the Lord hears. He is not looking for reasons to turn away; He is looking for a heart that turns toward Him. In truth, God delights in showing mercy, and He needs no other excuse than a sincere call for help.
None of us can stand before the Lord and demand healing as though we deserve it. Mercy, by its nature, is not receiving what our failings and finite bodies have earned. That is why I always encourage a prayer like yours: “God, have mercy.” We do not cry for justice, because justice would leave us all in our distress. We cry for mercy, and mercy has a name and a face, Jesus Christ. In Him, mercy and truth met together. He already carried our sorrows and our pains, so when He looks upon your friend’s suffering, He understands it fully and has made a way for compassion to flow.
You are doing the right thing by bringing this need before the Lord. Moses pled for a whole nation, and God, who had every reason to give up on them, instead responded with mercy because He is sovereign and good. He will have mercy on whom He will have mercy, and your friend can rest in the hope that God’s mercy is not measured out by how well we perform but by the abundance of His own heart.
Let your prayer be simple and persistent: “Lord, remember my friend in Your mercy. Look upon his pain, forgive whatever needs forgiving, and let Your healing goodness touch his body.” Trust that whether relief comes in an instant, through medicine, or as a gradual strengthening, the mercy of God will be his portion. His lovingkindness is better than life itself, and it endures through every test and every ache.
Keep praying with confidence. The God who made the heavens and stretched out the earth is the same God whose mercy is higher than the skies. He is near to the afflicted, and He will never dismiss a cry that trusts in His Son.