Bob Dylan and Johnny Cash, two of the all-time great American music icons, were friends and occasional collaborators. And one day in 1969, the two of them recorded a loose, informal session together, with rockabilly legend Carl Perkins sitting in on guitar. We’ve never heard that session, but we will soon. Dylan recently announced the forthcoming box set Bob Dylan (Featuring Johnny Cash) — Travelin’ Thru, 1967–1969: The Bootleg Series Vol. 15. It’ll feature, among a great many other things, that sesson with Cash. And today, we get to hear maybe the most intriguing number from the whole set — Dylan and Cash working out a new Johnny Cash song together.

Johnny Cash opened At San Quentin, his classic 1969 live album, with a song called “Wanted Man.” Bob Dylan wrote that song. (Years later, Cash also released a studio version.) As it turns out, Dylan had just given Cash the song a week earlier. Today, Dylan’s archivists have shared a music video for the first-take demo of “Wanted Man,” made in that day in 1969, when Dylan was 27 and Cash was 36.

At the beginning of the recording, we hear Cash’s wife June Carter Cash telling Cash to make sure and get the song down and maybe offering a bit of music criticism: “Be sure that Bob puts the melody for that song, that ‘Wanted Man.’ You forgot the melody.” And then we hear Dylan and Cash singing the song together — starting off serious, but eventually breaking up as Cash forgets the lyrics and then gets to chuckling about it. It’s a fascinating piece of behind-the-scenes music history. Below, check out that recording and the version of “Wanted Man” that ended up on At San Quentin.

Bob Dylan (Featuring Johnny Cash) — Travelin’ Thru, 1967–1969: The Bootleg Series Vol. 15 is out 11/1 on Sony Legacy.