Blake Shelton's friendship with songwriter Busbee was special. The country superstar recorded just one of the L.A.-based writer's songs, but their relationship clearly transcended music.

Busbee (real name Michael James Ryan) died on Sunday (Sept. 29), reportedly after a short battle with a rare brain cancer. Shelton took to Twitter soon after hearing the news, revealing that he and Stefani considered the 43-year-old a good friend. He had a huge part in crafting her You Make It Feel Like Christmas album (2017) — Busbee co-produced it and helped write six songs, including the title track, which was a duet with Shelton.

"Too much pain and unfairness, period," Shelton tweeted. "I guess sometimes you gotta dig extra EXTRA deep for peace to continue to have faith. And I will because Michael ALWAYS had faith."

Later, he tweeted the photo above. He was one of dozens of artists who shared memories of the literal hitmaker.

Check Out Busbee's Best Songs:

Shelton recorded just one of Busbee's songs for his own album ("Every Goodbye" from If I'm Honest in 2016) but he was part of two other collaborations that the well-known and respected songwriter co-wrote: Dia Frampton's "I Will" and Shakira's "Medicine."

Other artists Busbee wrote songs for include Maren Morris, Lady Antebellum, Rascal Flatts and Keith Urban. His biggest country hit may be "The Fighter," a double-platinum song from 2016. Busbee had been writing country songs for nearly a decade after starting off with interests in jazz. He leaves behind a wife and three kids.

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