It is narrated from Sayyiduna Abu Shurayh al-Khuza'i (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Whoever believes in Allah and the Last Day, let him honour his guest. His special hospitality is one day and one night. It is not lawful for him (the guest) to stay with his host so long that he has to put him out. Hospitality is three days; whatever is spent on him after that is charity."
Hadith Referenceالمعجم الكبير للطبراني / باب الهاء / 18698