Pope Benedict XVI has promised "unconditional reverence and obedience" to his successor in his final greetings to cardinals before retiring.
Benedict urged his cardinals Thursday to work in unity so that the College of Cardinals is "like an orchestra" where "agreement and harmony" can be reached - a clear message to the conclave that will pick the next pope.
He said he would pray for the cardinals in coming days and weeks as they choose his successor.
Around 5 p.m., Benedict will leave the palace for the last time as pontiff and fly to the papal retreat at Castel Gandolfo.
There, at 8 p.m. sharp, Benedict becomes the first pontiff in 600 years to resign. The doors of the palazzo will shut and the Swiss Guards will go off duty.