Chaupai sahib is Gurbani composed by the tenth Sikh Guru, Guru Gobind Singh. This Bani is one of the five Banis recited by the initiated Sikh every morning.
Below is a beautiful rendering of Chaupai Sahib, with translation. Please listen; it is one of my favourite Banis:
Incidentally, there is a movement on by http://chaupaisahib.org/ to complete one million readings of Chaupai Sahib by June 2009, the 25th anniversary of the attack on Sri Darbar Sahib. You are required to contribute by reciting the Path and informing via the website.