Willie Nelson and Sturgill Simpson
Amy Harris/Invision/AP and AP Photo/Henny Ray Abrams

Flashback: Sturgill Simpson Joins Willie Nelson to Perform 'Mammas Don't Let Your Babies Grow Up to be Cowboys'

Those in the crowd on June 22, 2018 at the Riverbend Music Center in Cincinnati, Ohio were treated to a remarkable night of music when Willie Nelson's Outlaw Music Festival Tour rolled into town. Thankfully, a fan filmed some show highlights, like when Sturgill Simpson joined Nelson on stage for a rendition of "Mammas Don't Let Your Babies Grow Up to Be Cowboys."

Nelson recorded "Mammas Don't Let Your Babies Grow Up to Be Cowboys" with Waylon Jennings for their 1978 duet record, Waylon & Willie. Their version of the song, which was originally written by Ed Bruce and his wife Patsy in 1976, earned them a Grammy award for Best Country Performance by a Duo or Group with Vocal and shot to No. 1 on the country charts.

After performing "Mammas," Simpson stuck around on stage for a 12-minute jam session with Nelson, including covers of "Will the Circle Be Unbroken," "Living in the Promiseland" and "I Saw the Light."

Read More: See Margo Price and Sturgill Simpson Cover 'After the Fire is Gone' at the Ryman

Willie Nelson's Outlaw Music Festival, presented by Blackbird Presents and Live Nation, returns in 2021. The tour will kick off in Austin, Texas on August 22 with Nelson & Family, Chris StapletonRyan Bingham and Yola set to headline.

Sturgill Simpson, Gov't Mule, Margo PriceKathleen Edwards, Nathanial Rateliff and the Night Sweats, Lucinda Williams, Ida Mae and The Avett Brothers will also perform on select dates.

Tickets for the tour went on sale on May 27.

"The Outlaw Music Festival Tour has always been about family and friends coming together for a great day of music and fun, and with the amazing group of artists joining us, this year promises to be our most special Outlaw Tour to date," Nelson said in a statement.

Now Watch: The Most Memorable Willie Nelson Collaborations