The 47-year-old actor remembered his former co-star at an advance screening of Furious 7 on Monday. Diesel attended the event hours after welcoming his third child with girlfriend Paloma Jimenez, and told the audience filming the sequel was difficult.
"This was a labor of love," he said of the seventh franchise installment. "It was, in some ways, the hardest movie I've ever had to do, because the relationships that you see on film are so real. When the tragedy happened, I lost my best friend. I lost my brother."