John 15:5:

I am the vine, ye are the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing.

See also:

The Healing Anointing
YOU Can Do Miracles
Preparing to Minister Healing
Do We Already Have Healing in Our Born-Again Spirits?
Objection: If Hebrews 13:8 Really Means What Faith Healers Say It Does, Jesus Will Be Healing Us Forever in Heaven as He Did on the Earth