Hadith

Jabir (radi Allahu anhu) reported that the Messenger of Allah (sal Allahu alaihi wa sallam) said, “If a person mentions the Name of Allah upon entering his house and eating, Shaitan says, addressing his followers, ‘You will find no where to spend the night and no dinner (here).’ But if he enters without mentioning the Name of Allah, Shaitan says, ‘You have found (a place) to spend the night,’ and if he does not mention the Name of Allah at the time of eating, Shaitan says, ‘You have found (a place) to spend the night as well as food.’” [Sahih Muslim]

Commentary: Ideally one should memorize the Sunnah duas which are said before beginning to eat and on entering one’s house. But if these are not memorized then one should at least say ‘Bismillah’ with the intention of entering into Allah’s protection.