Brett Eldredge has shared a new song, but it's not a radio single or a track he wrote for an album: It's a dedication to his big brother, in honor of his wedding day. On Instagram, Eldredge shared video footage of himself performing the song during his brother's wedding reception, accompanied solely by acoustic guitar -- and a few tears! Press play above to watch.

"I woke up very emotional in the middle of the night a few months ago with the realization that my big brother was about to get married and that we were no longer kids anymore," Eldredge explained in the caption of his post. "I had been putting off writing my best man speech until it came to me at 3am and I wrote the whole thing in bed that night."

The ballad speaks directly to his brother, remembering the times they spent together as kids and offering a hope for his brother's future family. "When you start a family of your own / I hope your kids run wild like we did back home / Barefoot in the grass, never thinking we would grow up fast / and then we did...."

Eldredge was visibly emotional as he sang. "Though it's almost impossible to sing through the tears, hopefully you will at least hear my heart for my brother, my best friend," he commented.

Next up, the country crooner will turn his talents to a more holiday-themed setting. He's scheduled to perform a couple of Christmas classics alongside a host of other artists during the Christmas in Rockefeller Center tree lighting ceremony on Dec. 4. The performance will be broadcast live in a special airing on NBC.

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