I heard Messenger of Allah (ﷺ) saying, "He who believes in Allah and the Last Day, should accommodate his guest according to his right." He was asked: "What is his right, O Messenger of Allah?" He (ﷺ) replied: "It is (to accommodate him) for a day and a night, and hospitality extends for three days, and what is beyond that is charity."

[Al-Bukhari and Muslim].

In Muslim it is added: Messenger of Allah (ﷺ) said, "It is not permissible for a Muslim to stay so long with his brother till he makes him sinful." He was asked: "O Messenger of Allah, how can he make him sinful?" He replied, "He prolongs his stay with him till nothing is left with the host to entertain him (guest)."