Romans 12:19:

Dearly beloved, avenge not yourselves, but rather give place unto wrath: for it is written, Vengeance is mine; I will repay, saith the Lord.

See also:

If You Blow It
Sin, Punishment, Sickness and Satan
Healing and the Lord’s Supper
Sickness as Chastening and Judgment in the New Testament
Healing and Repentance
Does Satan Have the Legal Right to Afflict Me if I Leave a Door Open to Him?
Does Satan Literally Invent All Diseases?
Did God PUT Sickness on Old Testament People or ALLOW the Devil to Do It?
Am I Sick Because God Has Turned Me Over to the Tormentors for Not Forgiving Someone?
Objection: Jesus Literally Said to “Keep On Asking.”  Therefore, We Should Bug God Like the Widow in Jesus’ Parable.
Notes on Acts 12:21-23
Notes on Hebrews 11:28