The pupil set him to watering a flower, but Beezlebub went on watering it until the room was filling with water. At that point, the man, having remembered he left his book unlocked, returned and dispelled Beezlebub.
A pupil tasked the man with watering a flower, but Beezlebub went on watering it until the room overflowed. The man then recalled he'd left his book unlocked and dispelled Beezlebub.