US President Barack Obama says the whole world is concerned about the condition of the suffering former president Nelson Mandela, and we are praying for him. President Obama said this in South Africa where on Friday he began the second leg of his three-country African journey. The visit comes at a touching moment, with former South African president and anti-apartheid hero Nelson Mandela seriously sick in a Johannesburg hospital. - Following his visit to South Africa, Obama is scheduled to go to Tanzania. He traveled to South Africa from Dakar, Senegal.