The Oak Ridge Boys' latest album, Rock of Ages: Hymns and Gospel Favorites, features mostly traditional hymns that the four men -- Duane Allen, Joe Bonsall, William Lee Golden and Richard Sterban -- grew up listening to as children. But one song on the album is a brand-new track: "Sweet Jesus" was penned by Merle Haggard, and the country legend wrote it with the award-winning quartet in mind.

"My son, Paul Martin, was playing with Marty Stuart and the Fabulous Superlatives," Allen recalls to The Boot. "They were doing the RFD television show, and Merle was a guest. So Merle came in and gave Paul a CD of a song and said, ‘I wrote this. Would you get it to Duane and see if he’ll record it?’"

Allen knew right away that the song was something he wanted for the Oak Ridge Boys, even though he wasn't sure if or when there would be a project on which it would fit.

"I listened to it, and I loved it," Allen recalls. "I called Merle, quite a bit before we cut the album, and said, ‘Merle, I’m sending out right now a live album. It doesn’t fit that, because the album’s of hits. And I’m about to mix a Christmas album. It doesn’t fit that. But if you will wait a little bit, I think I’m going to cut a hymns album somewhere down the line. If you’ll just hold it, I think I can get it on, and we can cut it.’ I didn’t know that Bill Gaither was going to call me and ask for a hymns album."

Thankfully, the Hag was understanding, and he allowed the group to hold on to the song until the timing was right.

"He said, ‘I’ll hold it as long as you want. I think it’s for you,'" Allen says.

When the guys finally went into the studio to record "Sweet Jesus," they realized that something was still lacking in the powerful song.

"I called Merle and said, ‘We’ve got these dates ready to go in the book, and we want to cut this song, but the recitation in the second verse, I don’t think I can do it justice,'" Allen explains. "'I think maybe it’s for you. Would you honor us with recording with the Oak Ridge Boys on this song you wrote for us. Would you consider that?’"

Thankfully, Haggard agreed and loaned his vocals to the song.

“We loved the recitation and thought if we could just get Merle to do that recitation, we would be thrilled,” Allen says. “But then, it worked so well that Merle just kept on singing with us on the last chorus — a once-in-a-lifetime experience for all of the Oak Ridge Boys. It is one of the biggest thrills of my career to get to sing and record with Merle Haggard.”

Rock of Ages: Hymns and Gospel Favorites is available on Amazon and iTunes.

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