Sayyiduna Abu Shurayh al-Adawi (may Allah be pleased with him) says: My ears heard and my eyes saw that the Messenger of Allah (peace and blessings be upon him) said: "Whoever believes in Allah and the Last Day, let him honour his neighbour; and whoever believes in Allah and the Last Day, let him honour his guest with his hospitality." It was asked: What is his hospitality? He (peace and blessings be upon him) said: "A day and a night, and hospitality is for three days; whatever is more than that is charity. It is not (permissible) for the guest to stay (so long) that it causes him (the host) hardship. And whoever believes in Allah and the Hereafter, let him speak good words or remain silent."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجزية / 18689