Pete Davidson introduces Miley Cyrus; Sean Lennon joins performance on 'SNL'

Dec. 16 (UPI) -- Sean Ono Lennon sang backup vocals and played guitar during Miley Cyrus' performance of his late father John's holiday song "Happy Xmas (War is Over)" on Saturday Night Live.

Cyrus and her collaborator Mark Ronson were the show's musical guests.

SNL cast member Pete Davidson introduced Cyrus and Ronson before the song started, and Cyrus mentioned Lennon's name at the end of the performance.

Davidson, who has been candid about his borderline personality disorder diagnosis, did not appear in any of the episode's live sketches after he made headlines for posting a disturbing message then deleting his social media accounts.

"I'm doing my best to stay here for you but I actually don't know how much longer I can last," Davidson wrote on Instagram in a now deleted posted. "All I've ever tried to do was help people. Just remember I told you so."

Deadline.com said the New York Police Department conducted a welfare check to make sure Davidson was OK.

Davidson's ex-girlfriend Ariana Grande and actor Jon Cryer both reached out to offer their support.

TMZ said Grande went to the Manhattan building where SNL is taped and tweeted: "I'm downstairs and I'm not going anywhere if you need anyone or anything. I know u have everyone u need and that's not me, but i'm here too."

"Am hearing Pete Davidson is at SNL and accounted for," Cryer tweeted. "We are thinking of you, Pete. You are loved. (And just a heads up, when you finally turn on your cell, it's gonna go ape(expletive) for a little while.)"

Earlier this month, Grande asked her fans to stop bullying Davidson online.

"No matter how hard the internet or anyone tries to make me kill myself. I won't. I'm upset I even have to say this," Davidson had written in his own defense.