The evening before you want to cook the soup, rinse the beans in colander, remove any debris, and place them in a large pot. Cover with water by at least 2-inches and soak them overnight. They will more than double in size so choose your pot accordingly. See alternate quick soak method in notes below.
The next day, drain and thoroughly rinse the soaked beans and transfer to a 6-quart slow cooker.
Layer the remaining ingredients through the ham bone in the slow cooker in the order listed. Add about 5 cups of chicken broth, or just enough to cover the beans and veggies. Reserve any remaining chicken broth for later. Tuck the bay leaves into the mixture, cover and cook on HIGH for 1 hour.
Reduce heat to LOW and continue to cook for an additional 5 to 6 hours. Stir occasionally during cooking time. When the beans are tender, remove the ham bone to a cutting board and remove and discard the bay leaves. Add the tomato sauce, stirring to combine. If you'd like a creamier texture, transfer about ⅓ of the soup to a blender or food processor and process until smooth. Return the puréed soup to the slow cooker, adding more broth, only if needed, to reach the desired consistency. Cover and continue to cook for an additional 20 to 30 minutes.
Meanwhile, pull the ham off the bone. discard the bone, and chop the ham into small pieces. Return the chopped ham to the slow cooker. Stir in the chopped parsley and taste and season with additional salt and pepper, as needed.