Question 5: What is the ruling on the Salaah (“Prayer”) of a person who has been in the habit of offering the Fajr (Dawn) Prayer after sunrise for two years? He claims that sleep overpowers him as he stays up late until midnight sitting at cafés or nightclubs.
Question 5: Is it permissible to dine with this person, keep company with him, or live with him?
A: It is prohibited to delay Salaah until its appointed time elapses. Every Muslim should give due concern to offer Salaah at its appointed time. He may ask someone to remind him of its time or he may set his alarm clock at prayer time. A person is prohibited to stay up late at night clubs or other places of entertainment which make him miss the Fajr Prayer or miss the reward of congregational prayer… read more here.