There is no single "most powerful" scripture for healing, as many scriptures offer different aspects of GOD's promise of healing, such as the following verses:
Exodus 15:26 “For I am the LORD that healeth thee.”
This verse identifies GOD with the name JEHOVAH RAPHA, "the GOD WHO HEALS.
Psalm 103:2-3 “Praise the LORD, my soul, and forget not all His benefits—who forgives all our sins and heals all our diseases.”
Psalm 34:19 “Many are the afflictions of the righteous, but the LORD delivers him out of them all".
Isaiah 53:5 “but He was pierced for our rebellion, crushed for our sins. He was beaten so we could have peace. He was whipped, and we are healed by His wounds.”
Jeremiah 17:14
“Heal me, LORD, and I will be healed; save me and I will be saved, for YOU are the one I praise.”
Jeremiah 33:6 “Nevertheless, I will bring health and healing to it; I will heal my people and will let them enjoy abundant peace and security.”
Matthew 8:17 “JESUS "took up our infirmities and carried our diseases.”
1 Peter 2:24 “He personally carried our sins in His body on the cross so that we can be dead to sin and live for what is right. 'By His wounds you have been healed’.”
James 5:14-15 “Is anyone among you sick? Let them call the elders of the church to pray over them and anoint them with oil in the Name of the LORD. And the prayer offered in faith will make the sick person well; the LORD will raise them up.”
3 John 2
“Beloved, I pray that all may go well with you and that you may be in good health, as it goes well with your soul.”
Prayer:
Dear Heavenly FATHER, I come to You today with a heart full of praise for the healing you have already provided in my life. Thank You for Your love and for Your power to restore health and bring comfort. I lift my hands and shout Your praise! I also ask for Your continued healing, strength, and peace for myself and for others who are in pain and suffering. Remind us that You are always with us, and help us to trust in Your perfect plan. In the powerful and victorious Name of JESUS, Amen.