Congress leader P Chidambaram said it's a black day in the constitutional history of India. He was speaking on the debate of Article 370 in the Rajya Sabha. "This is a very sad day. It is more than sad. In the constitutional history of India, this will be a black day," Mr Chidambaram said. He also said that no one would listen to them (opposition), appreciate their argument or change their mind. "It will be an absolute exercise in futility," he added.