Soak the beans overnight. Boil them starting from cold water. Wash the tripe and cut it into thin strips. Add the butter to a casserole dish and lightly sautÚ the chopped celery, carrot, onion and sage. When they begin to turn golden, add the tripe, stir and let the liquid absorb. Cut the tomatoes into small pieces and add them to the pot. Add salt and pepper to taste and cook for about 2 hours. Moisten with stock from time to time. 15 minutes before the end of the cooking time add the drained beans. Adjust the salt and pepper and allow to season. Serve the tripe hot, sprinkled with grated Parmesan cheese.