Rest in Hallowed Ground Quest/Spoiler

Method
You need to have The White Raven Monastery Quest (access to the Isle of the Kings) done to do this quest. Talk to Amanda in Edron Temple. Ask about a mission. She will ask you to bring her a vial of holy water from the White Raven Monastery. Travell to the Isle of Kings and ask the priest there to give you some. Tell him Amanda sent you.

Take the water back to Amanda. She will ask you to put some on every grave in the Unholy Cemetery, north of Edron (here). Be prepared to face Poachers and Hunters on your way to the cemetery, and ghouls on it.

Use the vial on every grave there. There are 15 graves, after using all graves, your vial will be empty. Report back to Amanda to get your reward.

''You see a package of potions. It weighs 36.00 oz. It contains 5 health and 5 mana potions.''

Transcripts

 * Amanda in Edron

Player: Hi Amanda: Welcome to the temple of Banor's blood Player. Player: Mission Amanda: Well, I would do it myself but I can't leave town for a longer time. Would you be so kind to bring me a vial of holy water from the white raven monastery? Player: Yes Amanda: I thank you a lot in advance. The power of the holy water from the white raven monastery is legendary. For my task it is indispensable. We talk about that when you get back.

Player: Hi Costello: Welcome, Player! Feel free to tell me what has brought you here. Player: Holy water Costello: Who are you to demand holy water from the white raven monastery? Who sent you?? Player: Amanda Costello: Ohh, why didn't you tell that before? Sure you get some holy water if it is for Amanda! Here you are.
 * Costello on Isle of the Kings

Player: Hi Amanda: Welcome to the temple of Banor's blood Player. Player: Mission Amanda: Have you heard about the unholy graveyard north of Edron? Go there and spill some holy water on every grave. Once you are done, come back tome.

Player: Hi Amanda: Welcome to the temple of Banor's blood Player. Player: Mission Amanda: I appreciate your help. May Banor be always on your side. Here, your reward is this package which contains five mana and five health potions.