The passing of XXXTentacion has affected more lives than most could have ever fathomed, especially those closest to him. Singer Billie Eilish is one of them, and at a recent performance she dedicated a tear-jerking new song to her fallen friend.

On Saturday (Oct. 20), Eilish was performing on the first date of her 1 By 1 Tour at the Fox Theater in Oakland, Calif. At some point during the evening, the singer sat down at her piano and told the crowd, "I got into my emotions," before performing her newest song, "6.18.18."

"It's dark enough/The moonlight doesn't show/And all my love could never bring you home," she croons. "You're always on my mind/I called a thousand times/And I have to let you go, but I love you more and more than you could know."

The track's title represents the day XXXTentacion was fatally shot in Deerfield Beach, Fla. On the day of his death, the 16-year-old appeared extremely distraught on social media as she posted screenshots of their text message conversations and FaceTime calls.

"The strongest human being ive ever known," she captioned the photos. "All you ever did was care. i love you jah. this is so, so painful."

Ski Mask The Slump God, X's longtime collaborator and friend, has also teased a tribute song in recent months. Fellow 2017 XXL Freshman Ugly God dropped one on June 22 titled "Tear Drop," which remixes his freestyle from their cypher with Madeintyo and Playboi Carti.

Watch Billie Eilish perform "6.18.18," along with other clips from the show, below.

See Behind-the-Scenes Photos of XXXTentacion at the 2017 XXL Freshman Shoot