KUTHŪHALASĀLĀ SUTTA: DISCOURSE ON THE DEBATING HALL
“And, Master Gotama, when a being has laid down this body, and is not yet reborn in another body, what would you declare it’s fuel to be?”
“Vaccha, when a being has laid down this body, and is not yet reborn in another body, I declare that it is fueled by craving. For, Vaccha, at that time, craving is the fuel.”
I think this is an implicit proof of Gandhabba, in the suttas.