April 6, 2016 3:05 PM EDT

Country music legend Merle Haggard died after a battle with double pneumonia Wednesday, his birthday. He had just turned 79. The singer, songwriter, and instrumentalist has influenced many country artists thanks to his decades-spanning career and standards like “Okie from Muskogee” and “Fightin’ Side of Me.”

“He was my brother, my friend. I will miss him,” Willie Nelson said in a statement to EW.

Toby Keith wrote, “The greatest singer songwriter of my lifetime is gone. Thanks for the music and friendship. R.I.P. Hag.”

Below, see more tributes from various country musicians and celebrities.

This article originally appeared on EW.com

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