Luke 5:31:

And Jesus answering said unto them, They that are whole need not a physician; but they that are sick.

See also:

Just to Be Sure
Is It a Sin to Go to the Doctor or Take Medicine?
Should Christians Get Flu Shots?
Because God Says I Am Healed, Can I Assume That I Do Not Need Medical Insurance?
The Lord Is My Physician, So Do I Need Regular Checkups with an Earthly One?