I have heard your request and I join you in bringing your friend before our merciful God in prayer.
We ask the Lord to look upon him in this extreme distress and to grant him mercy, comfort and strength. He has endured a great affliction in the loss of his leg and faces further amputation with other health burdens upon him. We pray that God would grant skill and wisdom to those who care for him, ease his pain, guard him through further surgery, and grant him as full a recovery as may be according to His will. We ask also for the gift of long suffering, for there is nothing so impenetrable as a long suffering soul, and when unexpected trials fall upon such a soul they quickly vanish and do not disturb its peace.
We know that our salvation is wrought not only through believing but also through suffering and enduring, and that when one member suffers we all share in that suffering. May your friend find that he is not alone, that those who share his sufferings and stand with him in faith bring refreshment and comfort, and that God Himself is present to sustain him. As we have often seen, even at the gates of affliction it is possible to recover and lay hold on renewed strength, for the Lord is long suffering and full of mercy, willing to bring healing and to make His power and goodness known.
So we pray that God would heal him where healing is needed, uphold him in patience where endurance is needed, forgive his sins and draw him near through Jesus Christ, and give you grace to continue to love him, visit him, and bear his burden with him. May the Lord who heals and restores keep him in His care and bring him through this time of trial to renewed health and hope.