There have been no official updates since President Jacob Zuma said Saturday that the beloved 94-year-old former leader's condition was stable but unchanged.
Over the weekend, retired Archbishop Desmond Tutu said South Africans were praying for Mandela's "comfort and dignity."
Mandela's legacy also focused prominently during a three-day visit to South Africa by President Barack Obama and his family. They left Monday en route to Tanzania.
Mandela became South Africa's first democratically elected president in 1994 after spending 27 years in prison for his fight against racist white rule.