Government officials said the 94-year-old Mandela underwent a successful surgery for gallstones on Saturday. Officials say Mandela has been hospitalized since Dec. 8 for tests and later medical treatment for a recurrent lung infection.
President Jacob Zuma and delegates at a convention for the African National Congress political party honoured Mandela on Sunday in song. Mandela was a leader of the ANC and served as the nation's first democratically elected president under the party's banner.
Mandela is revered for being a leader of the struggle against racist white rule in South Africa. He served one five-year term as president before retiring from public life.