Narrated Jabir:
The Prophet said, "When nightfalls, then keep your children close to you, for the devil spread out then. An hour later you can let them free; and close the gates of your house (at night), and mention Allah's Name thereupon, and cover your utensils, and mention Allah's Name thereupon, (and if you don't have something to cover your utensil) you may put across it something (e.g. a piece of wood etc.)."