THE RAILWAYS ACT, 1989 – Chapter VIII – Section 55

55. Prohibition Against Travelling Without Pass or Ticket
(1) No person shall enter or remain in any carriage on a railway for the purpose of travelling therein as a passenger unless he has with him a proper pass or ticket or obtained permission of a railway servant authorized in this behalf for such travel.
(2) A person obtaining permission under sub-section (1) shall ordinarily get a certificate from the railway servant referred to in that sub-section that he has been permitted to travel in such carriage on condition that he subsequently pays the fare payable for the distance to be travelled.

Forward reference⇒Section 56