"A Song For You" was originally written by Russell in 1970 and famously covered by artists like Whitney Houston, Donny Hathaway, Aretha Franklin, and Ray Charles, whose rendition earned him a 1994 GRAMMY for Best Male R&B Vocal Performance.
Timberlake concluded the touching tribute by addressing his wife directly with a special message of appreciation, and he got some help from the emotional lyrics.
"You have taught me so much about what a true love means," he wrote. "I can't put into words that these last five years have meant to me, so… 'Listen to the melody ‘cause my love is in there hiding...' #Happy5thAnniversaryWifey #ASongForYou."
Biel also celebrated the couple's special day on Instagram, resharing the video of Timberlake in the studio and posting her own silly clip of the two goofing around with some Snapchat filters.
"How lucky am I?" she captioned the adorable vid. "Even if he’s initially skeptical, he always gets extra for me. #5."