In their first statement since Mandela's death, his family said they had "lost a great man," just as they had when South Africa's apartheid government imprisoned him for decades.
"The pillar of our family is gone, just as he was away during that 27 painful years of imprisonment, but in our hearts and souls he will always be with us," said the statement, read by family spokesman Lt. Gen. Themba Templeton Matanzima.
"His spirit endures. As a family we commit ourselves to uphold and be guided by the values he lived for and was prepared to die for," he said.
A national day of prayer and reflection has been declared for Sunday. The next day, South Africa's two houses of parliament will hold special sessions to pay tribute to Mandela.
South Africa expects overwhelming crowds and several world leaders to attend services honoring the anti-apartheid leader. Official services will begin Tuesday with a major memorial planned at FNB Stadium on the edge of Johannesburg's Soweto township. Government Minister Collins Chabane told journalists Saturday he expects massive crowds far beyond what the stadium's normal 95,000-person capacity could hold. He said there would be "overflow" areas set up.
It's not clear which ceremony world leaders will attend, either Tuesday's stadium memorial or the planned funeral service Dec. 15 in Qunu, Mandela's rural hometown in Eastern Cape Province.
U.S. President Barack Obama and his two predecessors, George W. Bush and Bill Clinton, already have indicated they will attend services in South Africa honoring Mandela.
Mandela's body won't be at the stadium event Tuesday, Chabane said. His body will rest in state Wednesday, Thursday and Friday at the Union Buildings in Pretoria, the seat of government power in South Africa's capital.
Mandela died Thursday at the age of 95 after battling a prolonged illness.
The Associated Press contributed to this report.