Proverbs 26:2:

As the bird by wandering, as the swallow by flying, so the curse causeless shall not come.

See also:

The Kingdom of God Is Here NOW
The Causeless Curse
Paper Roadblocks to Healing
Breaking Generational Curses?
Objection: If Jesus Never Got Sick Before His Atonement, He Did Not Fully Participate in Our Human Experience