Johannesburg - Doctors will conduct further tests on former president Nelson Mandela on Monday, the presidency said.
"President Nelson Mandela had a good night's rest," presidential spokesperson Mac Maharaj said in a statement.
"He is in good hands."
Mandela, 94, was admitted to a hospital in Pretoria on Saturday for "medical attention".
At the time, Maharaj said that, as had been said before, Mandela would "receive medical attention from time to time which is consistent with his age".
On Sunday morning, President Jacob Zuma visited Mandela in hospital and found him "comfortable, and in good care", Maharaj said.
He said the presidency thanked the public for their messages of support to Mandela and his family.
"We thank the media and the public for affording him, his family and the medical team the necessary privacy and space."
He said Monday was a special day for Mandela. He received the Nobel Peace Prize on 10 December 1993.
Defence Minister Nosiviwe Mapisa-Nqakula reportedly visited Mandela at One Military hospital on Monday. According to the Associated Press Mapisa-Nqakula said Mandela was "doing very, very well".