Defied the Cult of Andraste in "The Urn of Sacred Ashes"
Towards the end of your search for the Urn to heal the Arl, you'll come across the Cult of Andraste. After fighting hordes of them, you'll meet one of them who wants to talk. He'll offer you the chance of helping the Cult and still being able to heal the Arl. Reject his offer and continue on to find the ashes.
Whatever you do, DO NOT hit the gong. You won't be able to win the fight that comes until later in the game.