Vin Diesel paid tribute to Paul Walker on his Facebook page on Monday night, calling the late actor a "brother … on and off screen."
Diesel posted a photo of himself with Walker, who died Saturday in a fiery car crash in Valencia, Calif., with a quote from Scottish poet Thomas Campbell: "To live in the hearts we leave behind, is not to die."
He added: "Pablo, I wish you could see the world right now... and the profound impact, your full life has had on it, on Us... on me...I will always love you Brian, as the brother you were... on and off screen."
Brian, of course, is a reference to Walker's role in the Fast & Furious film franchise, in which he starred opposite Diesel.
After news of Walker's death broke, social media users began circulating comments purported to have been made by Diesel on Instagram and Twitter, but those turned out to be fake.
On Sunday, another Fast star, Tyrese Gibson, visited the crash site, where he broke down in tears.
Walker, 40, died during a break from shooting Fast & Furious 7. He had returned to Southern California and died when the limited-edition Porsche in which he was a passenger crashed.
The driver has been identified as Roger Rodas, a well-respected financial adviser and the CEO of Walker's company Always Evolving. (The duo met because of their shared passion for cars.)
Walker was in the area, just north of Los Angeles, for a car show and toy drive set up through his charity, Reach Out WorldWide. In 2010, he flew to Chile to help those injured in the 8.8 magnitude earthquake and earlier was involved in the effort to assist survivors of the earthquake in Haiti.
Universal and the team behind Fast & Furious 7 are facing a delay in production following Walker's death, but sources say the movie will not be abandoned entirely.
Pamela McClintock contributed to this report.