Sahih Bukhari Volume 008, Book 074, Hadith Number 311.

Narated By Jabir : Allah s Apostle said, "When you intend going to bed at night, put out the lights, close the doors, tie the mouths of the water skins, and cover your food and drinks." Hamrnam said, "I think he (the other narrator) added, 'even with piece of wood across the utensil.'"