In a large Dutch oven, heat oil over medium heat. When the oil shimmers, add the celery, onion, and a good pinch of salt. Cook, stirring frequently, until the vegetables soften, about 8-10 minutes. Add the garlic and cook, stirring constantly, for 1 more minute. Add the drained beans, ham hocks or ham bone, bay leaves, and 2 quarts (8 cups) of water. Bring to a boil; cover; reduce the heat to low, and simmer (covered) for about 2 hours, or until the beans and vegetables are tender.