What should one do if he has completely finished his meal and then remembers that he did not say "Bismillah" (in the name of Allah)? Is it permissible for him to eat or drink with the intention of saying "Bismillah" to avoid the participation of devils, or should he seek forgiveness and suffice with that?

"Whoever forgets to say 'Bismillah' at the beginning of a meal should say: 'Bismillah awwalahu wa akhirahu' (In the name of Allah, at its beginning and its end). If he only remembers the Basmala after finishing the meal, there is no sin upon him for forgetting, as per the verse: 'Our Lord, do not take us to task if we forget or make a mistake.' It is not recommended to say 'Bismillah' after finishing a meal. As for eating a bite after intending to finish and saying 'Bismillah' over it, that is permissible, but it cannot be definitively said that it suffices for the Basmala during the meal itself. Saying 'Alhamdulillah' (praise be to Allah) after finishing does not replace saying 'Bismillah.' And reciting Surat Al-Ikhlas after finishing for someone who forgot to say 'Bismillah' is a fabricated hadith."