More than 50 years since the two music legends first met and became friends, Paul Simon and Bob Weir have finally performed their first duet together. Simon was playing the Outside Lands Music Festival in San Francisco Sunday night when he invited the Grateful Dead guitarist to join him on stage.

According to Simon, the two first met in San Francisco in 1967. Simon arrived at the house where the Grateful Dead were living, intending to invite the band to appear at the Monterey Pop Festival.

“I knocked on the door of the house, and Bob Weir opened the door,” he explained to the audience. “And we’ve been friends ever since. But actually, this is our first duet.”

Weir then joined him on stage and the two performed the Simon and Garfunkel hit, “The Boxer”.

Watch fan-filmed footage below.

Although Paul Simon officially retired from touring following his final Farewell tour this past September, the singer-songwriter has said that he will continue to play the occasional show and donate the proceeds to various causes, particularly those whose intention is to save the plant. He pledged to donate his performance fee from his Outside Lands festival to the San Francisco Parks Alliance and Friends of the Urban Forest.