Combine the drained chickpeas with enough water to cover by 2 inches in a large soup pot or Dutch oven, add the bay leaf, and bring to a boil. Reduce the heat and skim off any foam. Cover and simmer for 1 hour. Add salt to taste (about a tablespoon), and simmer for another hour, until tender. Drain over a bowl and retain 2 cups of the cooking liquid. Set aside.
While the beans are cooking, heat a large, heavy casserole over medium-high heat and when it is hot, add the sausages. Brown the sausages on all sides and remove from the heat. Slice and set aside.
Add the olive oil to the pan, turn the heat down to medium, and add the onion. Cook, stirring, until it begins to soften, and add the diced pepper. Cook, stirring often, until the onion and pepper are tender, 5 to 10 minutes. Add the garlic, stir together for a minute or two, until fragrant, and stir in the tomatoes, sliced sausage, thyme, and salt and pepper to taste. Cook, stirring often over medium heat for about 10 minutes, until the tomatoes have cooked down slightly. Add the chickpeas, dried cayenne or chili flakes, and the 2 cups of their liquid that you set aside. Bring back to a simmer, stir together, turn the heat to very low, cover and cook gently for 30 minutes to 1 hour, until the beans are very tender and the broth fragrant. Taste, adjust seasonings, and serve.