(CNN) - Country vocal quartet The Oak Ridge Boys sang a soaring rendition of "Amazing Grace" on Thursday to honor former President George H.W. Bush at his funeral in Texas, the final time they'd perform for a man who'd become a friend.
The first time the Oak Ridge Boys met Bush, he was a new vice president -- and running straight at them.
"The vice president comes tearing across the White House lawn," band member Joe Bonsall said Thursday in an interview with CNN, reminiscing on the encounter that took place when President Ronald Reagan invited the band to sing at a 1983 White House barbecue.
"Here comes George Bush running towards us, saying, 'I can't make it tonight, but I'm a huge country fan, I'm a big Oak fan. Will you sing some of your songs?' " Bonsall recounted.
The band -- who had been setting up for a sound check -- happily obliged, singing their hits of the day and lesser known songs like "Freckles," as Bush rattled off the names of tracks he wanted to hear.
"He started listing album cuts, so he wasn't kidding," Bonsall said. "We were just blown away that the vice president knew our music."
When they sang for Bush one last time on Thursday, their promise to sing at his funeral was the final marker on three decades of very musical friendship between four country singers and the former leader of the free world.
The band had concerts in Washington state scheduled for Wednesday and Thursday night, which made the idea of attending Thursday morning's service seem like a stretch at first. But a longtime friend of the band leased a private plane to get them to Texas on time, flying all night to arrive at 4:30 a.m. Thursday.
"We've been carrying a suit on our tour bus for a couple of months and wondering," Bonsall said. "By hook or by crook, we were going to be there for him."
Over the years, the band had several more engagements with the Bushes. Not only did they return to perform for 41 and 43's White House barbecues, they performed at first family birthday parties and even campaigned with Bush in 1991 and 1992.
Once, the then-President took the band behind the Oval Office to reveal a stereo set blasting their songs, Bonsall said.
"He said, 'Fellas, come here, I've got to show you something,' " Bonsall recalled. "I said, this is the leader of the free world, how he can hear anything with us blowing out of that speaker set?"
"We're singing (our song) 'Dig a Little Deeper in the Well, Boys' pumped up to 11, and he has the red phone right there, and I'm thinking, 'If that thing rings, he's not going to hear it,' " he added.
The Bushes used to invite The Oak Ridge Boys and their wives to their home in Kennebunkport, Maine for trips full of fishing, dinners and singing, Bonsall said. The band also attended Barbara Bush's funeral in April.
"He and Barbara have come to mean the world to us over all these years," Bonsall said, later adding, "We have experienced so many great moments with this great man over the decades."
Last summer, the band visited the former President at his home in Houston, and he half-jokingly asked them to sing at his funeral.
"We said, 'Of course we will, sir, but let's not talk about that,' " Bonsall said.
Right after Bush's death, the band's tour director was notified that the time had come. The Oak Ridge Boys were greeted with warm hugs from the Bush family when they arrived in Houston on Thursday morning.
"They all knew how much President Bush loved us and how much we loved him, and they all thanked us for being there. And it was so nice to be welcomed by the family," Bonsall said.
He said he had "no words" to describe the honor of being included in the service, and that all of the praise for Bush was deserved. Singing "for not only a friend but a president" was "one of the greatest honors of all time," he added.
"Singing 'Amazing Grace' with our great friend laying there in the coffin in front of you, it really brought it home for us that he's actually gone," Bonsall said.
"It was one of the greatest things that we've ever had the honor of doing," he added. "To say goodbye to him not only as a president and a world leader and a diplomat -- it was saying goodbye to a friend."
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