The South African statesman spoke critically in London about Robert Mugabe's crackdown.
That event now is being overshadowed by events in troubled Zimbabwe, where widely condemned elections are due to be held on the same day.
While brief, the phrase hit the headlines with many commentators reporting Mandela had "broken his silence." He retired from politics nine years ago.
Friday's concert will raise funds for Mandela's AIDS/HIV charity called 46664, named after his prison number during more than 25 years behind bars for his stand against South African apartheid.
It gives Mandela a more public platform to expand on his comments about Zimbabwe, but some of the performers argue such an approach could backfire. "That would not help," argued Emmanuel Jal, a Sudanese hip-hop artist based in London. "The more we finger-point him [Mugabe], the more the people in Zimbabwe suffer.
"The only way to save Zimbabwe is if he travels to Zimbabwe. Let it be a secret meeting, do things underground, find out what is in his [Mugabe's] mind."