Abu Dawud Book 21, Hadith Number 3741.
Chapter : Not known.
Narated By AbuKarimah : The Prophet (PBUH) said: It is a duty of every Muslim (to provide hospitality) to a guest for a night. If anyone comes in the morning to his house, it is a debt due to him. If he wishes, he may fulfil it, and if he wishes he may leave it.