Justin Bieber (1:30)
Nicole Scherzinger (1:38)
Jennifer Hudson (1:38)
Jennifer Nettles (1:46)
Josh Groban (1:52)
Tony Bennett (2:02)
Mary J. Blige (2:09)
Michael Jackson (2:22) (recorded clip only)
Janet Jackson (2:27)
Barbra Streisand (2:33)
Miley Cyrus (2:48)
Enrique Iglesias (2:59)
Jamie Foxx (3:10)
Wyclef Jean (3:15)
Adam Levine (3:24)
P! nk (3:29)
BeBe Winans (3:35)
Usher (3:48)
Celine Dion (3:51)
Orianthi (on guitar) 3:59
Fergie Ferguson (4:02)
Nick Jonas (4:19)
Toni Braxton (4:27)
Mary Mary (4:33)
Isaac Slade (4:38)
Lil Wayne (4:48)
Carlos Santana (on guitar) (4:58)
Akon (5:12)
T-Pain (5:39)
LL Cool (Rap)
Will.i.am (Rap)
Snoop Dogg (Rap)
Busta Rhymes (Rap)
Swiss Beats (Rap)
Iyaz (Rap)
Kanye West (Rap)
Chorus (in Alphabetical Order)
Patti Austin
Philip Bailey
Fonzworth Bentley
Bizzy Bone
Ethan Bortnick
Jeff Bridges
Zac Brown
Brandy
Kristian Bush
Natalie Cole
Harry Connick Jr.
Nikka Costa
Kid Cudi
Faith Evans
Melanie Fiona
Sean Garrett
Tyrese Gibson
Anthony Hamilton
Keith Harris
Rick Hendrix
Keri Hilson
Julianne Hough
Nipsey Hussle
Il Trio
India.Arie
Randy Jackson
Taj Jackson
Taryll Jackson
TJ Jackson
Al Jardine
Jimmy Jean-Louis
Ralph Johnson
Joe Jonas
Kevin Jonas
Jones
Gladys Knight
Benji Madden
Harlow Madden
Joel Madden
Katharine McPhee
Jason Mraz
Mýa
Plain Pat
Freda Payne
A. R. Rahman
RedOne
Nicole Richie
Raphael Saadiq
Trey Songz
Musiq Soulchild
Jordin Sparks
Robin Thicke
Rob Thomas
Vince Vaughn
Verdine White
Ann Wilson
Brian Wilson
Nancy Wilson
Ustin Bieber, Lil Wayne, Wyclef Jean, Josh Groban, Will.I.Am, T-Pain, Kanye West, Bizzy Bone, Kid Cudi, LL Cool J, Snoop Dogg, Drake, Mann, Nipsey Hussle, Busta Rhymes, Swizz Beatz, Miley Cyrus, Keri Hilson, Zac Brown, Barbra Streisand, Carlos Santana, Natalie Cole, Winans BeBe, Freda Payne, Harry Connick Jr., Earth, Wind & Fire, Brian Beach Boys "Wilson & Al Jardine, Tony Bennett, Rahman, Randy Jackson, Patti Austin, Celine Dion şi Gladys Knight, Jeff Bridges, Vince Vaughn, Lionel Richie şi Quincy Jones, Nicole Richie, Rashida Jones, Taj, Taryll şi TJ Jackson, Joel si Benji Madden, Akon, Brandy, Melanie Fiona, Mya, Musiq Soulchild, Katharine McPhee, Trey Songz, Faith Evans, Jimmy Jean-Louis, Orianthi, Sugarland, Jennifer Hudson, Jason Mraz, India Arie, Mary Mary, Tyrese Gibson, Raphael Saadiq, Roz, Jordin Sparks, Rob Thomas, Usher, Isaac Fray lui Slade, Ethan Bortnick, Enrique Iglesias, Robin Thicke, Jamie Foxx, Maroon 5, Adam Levine, Jonas Brothers, Nicole Scherzinger şi Julianne Hough.