The "Austin" singer remembered his late friend following his death on Monday
“Even though I knew about your battle these last few months I still never imagined this day. Anyone who knew you knows what I mean,” wrote the 47-year-old singer on Tuesday. “You were the toughest man I ever met.”
"Thank you brother for being a friend, a hero and an inspiration. There will never be another Toby Keith,” concluded the fellow Oklahoma native.
During the 2023 People's Choice Country Awards last September, Shelton presented Keith with the country music icon award.
At the time, Keith told PEOPLE that he had known Shelton “forever.”
“I took him out when I first got headliner status early on and I was his first big tour he got,” said the late musician.
“He lived in Oklahoma, so we're kindred spirits, a lot alike,” Keith added. “We have fun together.”
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Along with Shelton, several more country music stars mourned the loss of the icon — including Carrie Underwood, Dolly Parton, Jason Aldean, Old Dominion, Luke Bryan, Jelly Roll, Zach Bryan, Dan + Shay and Luke Combs, as well as Reba McEntire and Chuck Wicks.
McEntire told PEOPLE, "We're going to miss him so much, not only as a friend but a fellow performer and person in the music business and from Oklahoma.”
"But he doesn't have to fight anymore, and he doesn't have to hurt anymore," the 68-year-old singer added. "I hope one day to get to see him up in Heaven. Thank God we have his wonderful music to keep us company, even though he's not here on earth with us."
"Well, I'm like any other fan, right? I love Toby Keith. I loved his music, grew up with his music,” Wicks, 44, told PEOPLE on Tuesday. "He was always bigger than life. And I think that's what people loved about him so much is, he's this big guy up there, bigger than life guy singing hit song after hit song."
Throughout his decades-long career, Keith captivated audiences with chart-topping country hits, including "Should've Been a Cowboy," "I Love This Bar," "As Good as I Once Was," and "Made in America," among others.
Related: Toby Keith's Life in Photos
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