Engineer Louis Bell recalled the day in January 2016 when Justin Bieber visited Post Malone in the studio.
"We were halfway through (Stoney
) and ended up renting a house," he explained to Billboard
. "Post started bringing me in to pull together every song he was working on, so on the first day Justin came in and we played him a track that (fellow producer) Frank Dukes had done."
Bieber immediately jumped on Dukes' beat and he and Malone concocted what would become "Deja Vu." Bell recalled: "He ended up freestyling the whole song in the booth, and him and Post went back and forth with ideas. The whole time I'm engineering and recording it, which kept me on my toes."