CHICAGO (CBS) – The Rev. Jesse Jackson Sr. has been in touch with the family of international icon Nelson Mandela, who spent the night in a Johannesburg hospital.

Mandela — the anti-Apartheid activist who spent years in prison before becoming South Africa’s president – was admitted for a lung infection, CBS News reported.

“The family is gathering close to him at the hospital in South Africa. So want to hope and pray that he recovers,” Jackson, founder of the Rainbow/PUSH Coalition, told CBS 2’s Dorothy Tucker.

Jackson is concerned about his friend. He spent the night talking to Nelson Mandela’s current wife and daughters. The 92-year-old Mandela is undergoing tests.

“He’s fragile. He’s weakened by the long years of imprisonment and the toll his age has taken on him,” Jackson said.

Jackson says while Mandela’s family hasn’t shared the specifics of his condition there are indications he’s gravely ill. He says he’s surrounded by political leaders, close family and friends and his former wife and political activist, Winnie Mandela.

“She left in tears and that was quite suggestive …  he’s very ill,” Jackson said.

Jackson saw Mandela just six weeks ago, when he was in South Africa giving a speech. He says they got a chance to talk for 15 to 20 minutes.