Sahih Muslim Book 23, Hadith Number 4998.
Chapter : Command pertaining to the covering of vessels, and tightening (the mouths) of waterskins, etc.
Jabir reported Allah’s Messenger (may peace be upon him) as saying: Do not let your animals and children go out when the sun sets until the first and the darkest part of the night is over, for the Satan is let loose with the sinking of the sun until the darkest part of the night is over.