Feldstein, who is the brother of actors Jonah Hill and Beanie Feldstein, died in December 2017 from a pulmonary thromboembolism. He is seen as the man responsible for the rise of Levine's band, Maroon 5, thanks in part to his management over them throughout their career.
In Levine's farewell message, he concluded with a kind thought about Jordan, who was the reason he joined the show in the first place.
"And Lastly, I’d like to thank my manager Jordan for convincing me to take that meeting," Levine wrote. "What an amazing ride. Thank you all so much."
Levine has publicly discussed Feldstein's passing a few times since the music mogul's death at age 40.
"It was a tragedy foisted upon us and far and away one of the saddest moments of our lives, and personally of mine. This is a kid I’ve known since we were in diapers. He was one of the most important people in my life from a very early age,' Levine told Variety in November 2018. "It (his death) was brutal. When that all went down, I remember having to dig deep and say to myself, 'Am I just going to let this fall apart, or am I going to try and hold this thing together?' In chaotic situations that are so horrific and so gut-wrenching, you have to kind of show up, you know? Take the reins cautiously but still optimistically. Take control without having too much to deal with.
"I thought to myself, 'How do I make this all work again?' I know that he would have wanted me to hold it together."
Elsewhere in his goodbye message, the Maroon 5 vocalist also thanked producer Mark Burnett and NBC for working with him for so long.
"About 8 years ago, Mark Burnett convinced us to sign up for this show where you sit in a big red chair with your back turned away from the singers on the stage. First thank you must go to Mark," he wrote. "We had no idea what we were doing or where it was going. After the first day of shooting, I sat there, stunned. I said to myself 'There's some magic here. Something is definitely happening.' It went on to be a life shaping experience that will be close to my heart forever.
He added, "Thank you NBC for signing me up. I am truly honored to have been a part of something I’ll always cherish for the rest of my life. Thank you to every single coach I ever sat in those chairs with. That is shared experience that is singularly ours. We have that for life. Thank you to everyone who supported this long strange and amazing left turn into a place I never thought I’d go."
He also went on to thank Carson Daly, who he called "the backbone" of The Voice, and many other behind the scenes.
"Thank you Carson Daly for babysitting the musicians and making sure our shoes were tied and we had our lunch boxes. You are the backbone of this thing and we appreciate you more than you know," Levine wrote. "Thank you to the people behind the scenes who do the real work and make this machine hum. To the amazingly talented vocalists who competed on the show and blew my mind on a daily basis."
He also closed things out with a shout-out to Blake Shelton, who has also coached since the show's first season. He additionally thanked current coaches Kelly Clarkson and John Legend, despite not working with them as long.
"And, BLAKE F—IN’ SHELTON. I couldn’t hide my love for you if I tried. Seriously. I tried. Can’t do it. Our friendship is and always will be one for the books," Levine wrote. "Whatever this whole surreal experience was, Im just happy I got to experience it with you. You’re my brother for life. Kelly and John, take care of the cowboy and I’m sure I’ll be back to say hi very very soon. So much love to you both.0comments
He added, "And lastly, to all of the loyal Voice fans, there’s literally no show without you guys. For me, it was time to move on. Your support has meant EVERYTHING."
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