The music professor said he 'immediately' thought of Legend and wife Chrissy Teigen when singing the emotional song.
The music professor from Texas took the stage on Monday to show off his superhuman range as the Top 9 performers competed for a chance in next week's finals. It was Fan Appreciation Week, so the crooner's cover of Coldplay's "Fix You" celebrated his supportive grandmother and of course his legion of fans -- who have termed themselves the "Holibaes" -- but it was also intended as a heartfelt choice for his coach.
Holiday said he "instantly thought" of Legend and wife Chrissy Teigen -- who lost their third child, son Jack, in September -- when he decided to sing the song. And the emotional lyrics, as well as Holiday's performance, brought the two men to tears.
"I was just sitting there working, and we started playing this song," Legend recalled of rehearsing the song. "My wife was sitting next to me, my daughter's in my wife's lap. We all just started crying... The lyrics of the song just spoke to us."
"Going though what we went through as a family this year, and what so many families around the world go through -- there's just a lot of folks out there who are struggling and could use this message," Legend added.
The coaches were blown away by Holiday's performance. "The last part of that broke me in a way that I had to shut off," Kelly Clarkson admitted, as Legend called the performance "beautiful."
"I mean, I'm crying over here," the coach admitted through tears. "When I talked to John about this song, I said it would mean a lot to us if you just give you emotional best performance and let yourself be not perfect, let yourself just live in the emotional of the song. And we felt it."
The Voice airs Mondays and Tuesdays at 8 p.m. PT/ET on NBC.