Common previously teamed up with singer John Legend to create the Oscar-winning Glory, the theme tune for 2014 film Selma, but he reveals it took some convincing before Ava agreed to use another of his tracks, A Letter to the Free, on her latest project.
He recalls rapping the first verse of the tune in her ear as they attended a birthday party for U.S. President Barack Obama in August (16), but his timing wasn't the best.
"She was listening, but with the President and the First Lady standing seven feet away, she was trying to pay attention to them, too," he laughs to The Hollywood Reporter.
Ava admitted she wasn't too keen on the idea at first, but after paying closer attention to the lyrics of the tune, she had a change of heart.
"(She said), 'I don't want people to say we tried the same collaboration again,'" he told the publication. "I was like, 'Ava, (Selma actor) David Oyelowo's been in two of your films...'"
He continues, "After she sat with the song, she loved it. This film can change culture, especially when it's shown in places of education. My biggest desire is to be a part of work that has that kind of impact."
The lyrics to A Letter to the Free address the ongoing racial tensions between the white and African-American communities, a topic studied in Ava's new documentary, which examines the links between racial inequality in the U.S. and the nation's prison system.
One line heralds "America's moment to come to Jesus", referring to a difficult moment of truth, which Common believes is more relevant than ever in light of Donald Trump's election as the next president of the U.S., after the Republican candidate made a series of offensive remarks regarding women, Muslims, Mexican immigrants, the disabled, and others throughout his election campaign.
"We're having a come-to-Jesus moment (now) because we've seen something happen that no one ever thought would," he explains of Trump's shock win over his Democratic rival Hillary Clinton.
However, Common is hopeful those concerned about the current state of the country will be encouraged to fight for a better world.
He adds, "We've got to think about the complexities within our country. I'm not inhuman. I woke up the day after the election with a heavy heart. But I'm still a believer. It's what Frederick Douglass said: 'Without struggle, there is no progress.'"