Rush Limbaugh left a lasting impact on country star John Rich.

Limbaugh died at the age of 70 on Wednesday and was honored by the "Earth to God" singer on Twitter, in which he revealed the radio pioneer had anonymously made a large donation to charity.

"When I was on 'Celebrity Apprentice,' Rush Limbaugh made a donation of $100,000 dollars to St Jude Children's Hospital to support them, and my mission on the TV Show under the condition that he remained anonymous," Rich, who appeared on the show in 2011, tweeted. "I never said a word until now. He will be missed. #RIPRushLimbaugh."

The country singer spoke further about the donation with Fox News.

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"Part of my whole goal [on 'Celebrity Apprentice'] was to raise as much money as I could for ... St. Jude Children's Research Hospital in Memphis," Rich, 47, explained. "My goal was to try to raise above a million dollars, which had never been done before on that show."

The host of Fox Nation's "The Pursuit!" said that when he reached out to several friends to ask for donations at the time, Limbaugh was among them.

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"When I asked Rush Limbaugh about that, he said, 'I would love to make a donation, but it has to be anonymous. Don't tell anybody it came from me, don't tell [host] Donald Trump it came from me, don't talk about it in any way, shape or form,'" recalled the singer, adding that Limbaugh said he likes to donate to great causes anonymously.

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"I didn't know what he was going to donate until it showed up," Rich continued. "When it showed up, it was $100,000 to the kids at St. Jude Children's Research Hospital and I couldn't tell anybody where it came from."

The Big & Rich member found the generous donation to be "such a striking characteristic" of Limbaugh. Rich recalled instead of Limbaugh wanting "a lot of praise for an action that big," he made the star "promise he would get no praise for it."

John Rich (right) recalled receiving a donation of $100,000 from Rush Limbaugh (left) under the condition on anonymity to go toward St. Jude Children's Research Hospital during the singer's stint on 'Celebrity Apprentice.' (Getty Images)

Rich ended up raising $1.4 million during the show's 11th season, which he said is still a record-holding amount for "Celebrity Apprentice."

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"I just thought it was a really respectful move on his end to do a great thing for those kids at that hospital and support my efforts on that show and just something that really stuck with me over the years," added Rich.

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Reps for St. Jude Children's Research Hospital did not immediately respond to Fox News' request for comment.