We know they're friends and exist in the same wheel house (not to mention the Scooter Braun connection), but, to this day, we haven't heard a Bieber/Ariana collaboration or even a real mention of one.
Thankfully, someone has mashed up Ariana's Grande's "One Last Time" and Bieber's chart topping "What Do You Mean?" and it sounds like true perfection.
The two songs suit each other surprisingly well despite having quite different vibes. Bieber's vocals are slightly pitched up to better suit Ariana's part.