Job 42:10:

And the LORD turned the captivity of Job, when he prayed for his friends: also the LORD gave Job twice as much as he had before.

Notes on Job 42:10:

Satan made Job sick.  God healed Job and called his sickness captivity.  To whom or what was he captive?  Jesus called sickness the bondage of Satan (Luke 13:16) and Peter called it the oppression of the devil (Acts 10:38).

We see an example of sowing and reaping here where Job was healed as he prayed for his friends.

See also:

Notes on Luke 4:18-19
The Baseball Diamond of Healing
Who or What Causes Sickness?
Job Explained
Can God Use You to Help Others When Your Own Life Is Full of Problems?
Objection: Job Was a Godly Man, Yet God Let Him Get Sick
Objection: Sickness Is a Blessing in Disguise
Objection: Jesus Only Said That He Was Sent to Heal the Brokenhearted, Not the Sick
Objection: Like Any Loving Parent, God Sometimes Has to Tell His Children NO for Their Own Good
Objection: Any Other Objection Not Specifically Covered in This Book
Condition: Boils
Condition: Breathing Difficulties (Also Referenced Under Asthma)