Rinse beans. Place in a large pot and cover with water. Bring to a boil. Remove from heat, cover, and let stand 1 hour. Rinse beans again and add fresh water to cover.
Add red onion, garlic, celery, carrots, salt, pepper, bay leaves, oregano, and parsley. Bring to a boil. Reduce heat and simmer covered, over low heat for 2 hours. Stir occasionally.
Preheat oven to 350 degrees F (175 degrees C).
Remove bay leaves and place bean mixture into a 3 quart casserole pan. Stir in butter. Mix thoroughly. Cover and bake for 1 hour (until beans are tender).
