In an oblique reference to the Gujarat riots, Congress chief Sonia Gandhi yet again hit out at the NDA Government. And though the two shared the dais, PM A.B. Vajpayee kept his cool — probably because the occasion was a celebration to mark 50 years of Parliament. ‘‘The biggest challenge facing the country, as recent incidents show, are the fanatic and communal forces. The Parliament is a foundation of India’s democracy; we cannot side-step our responsibility,’’ Sonia said at the newly constructed Library complex in Parliament House to take part in the celebrations.She went on: ‘‘we have to assure our people that India belongs to each one of them,’’ and added: ‘‘If this is an occasion for celebrations, it is also an occasion for reflection.’’Vajpayee, instead of crossing swords with her, listened quietly and later said the Parliament represented the country’s unity. He said: ‘‘It speaks for the aspirations of a 100 crore people, protects their rights and guides them to their duties.It guarantees respect for all religions.’’