What should a person say when he realizes after he has finished eating that he forgot to say Bismillaah?
Question

                After I had finished eating my meal and I wanted to praise Allaah after finishing eating, I remembered that I had not said Bismillaah. Should I say Bismillaah awwalahu wa aakhirahu, alhamdulillaah (In the name of Allaah at the beginning and the end, praise be to Allaah)? Or should I say Alhamdu-Lillaah only? Or what? Please advise us, may Allaah reward you with good.
Praise be to Allah.
    What is prescribed for the one who forgets to say Bismillaah 
    when he first starts to eat is to say when he remembers, Bismillaah 
    awwalahu wa aakhirahu (In the name of Allaah at the beginning and the 
    end) or to say Bismillaah fi awwalihi wa aakhirihi (In the name of 
    Allaah at the beginning and the end). 

    It was narrated from ‘Aa’ishah (may Allaah be pleased with 
    her) that the Messenger of Allaah  (peace and blessings of Allaah be 
    upon him) said:  

    “When one of you eats, let him remember Allaah at the 
    beginning, and if he forgets to remember Allaah at the beginning, let him 
    say Bismillaah fi awwalihi wa aakhirihi (In the name of Allaah at the 
    beginning and the end).” Narrated by al-Tirmidhi (1857), and he said: it is 
    hasan saheeh. 

    The phrase “and if he forgets to remember Allaah at the 
    beginning, let him say…” includes both the one who remembers to say 
    Bismillaah whilst eating, or at the end, or shortly after he has finished 
    eating, because of the general meaning of the hadeeth. 

    It says in Kashshaaf al-Qinaa’ (5/173): The apparent 
    meaning is even if that is after he has finished eating.

     It says in Mughni al-Muhtaaj (4/411): 

    If he forgets to do it (i.e., say Bismillaah) at the 
    beginning, he may say it partway through, and if he forgets it partway 
    through, he may say it at the end. End quote. 

    It says in Nihaayat al-Muhtaaj (1/184): 

    He should not say it (i.e., Bismillaah) after finishing 
    wudoo’, which is unlike the case with eating, where he may say it 
    afterwards. End quote. 

    It says in al-Haashiyah ‘ala Nihaayat al-Muhtaaj: 

    Meaning, that if the time between finishing his meal and 
    remembering is not too long, he may say it. What is too long is to be 
    determined by what is customary. End quote. 

    The hadeeth also indicates that saying Bismillaah fi 
    awwalihi wa aakhirihi (In the name of Allaah at the beginning and the 
    end) takes the place of saying Bismillaah at the beginning, and the reward 
    for seeking the help of Allaah when starting to eat will be recorded for the 
    Muslim, as a honour and a bounty from Allaah, may He be blessed and 
    exalted. 

    Al-Munaawi said in Fayd al-Qadeer (1/296): 

    How can it be true that one has sought the help of Allaah at 
    the beginning when he did not do that at the beginning?  

    Because we say that the phrase indicates that this is the 
    case, thus the one who utters this phrase becomes like one who sought help 
    at the beginning and will get the same blessing as one who sought help at 
    the beginning. End quote. 

    The Sunnah for the one who has finished eating is to praise 
    Allaah for it in different ways, such as the following. 

    It was narrated from Abu Umaamah (may Allaah be pleased with 
    him) that when his meal was cleared away, the Prophet  (peace and 
    blessings of Allaah be upon him) would say: “Al-hamdu Lillaahi hamdan 
    katheeran tayyiban mubaarakan fihi ghayri makfiyyin wa laa muwadda’ wa laa 
    mustaghni ‘anhu Rabbanaa (Allaah be praised with an abundant, beautiful, 
    blessed praise. He is the One Who is Sufficient, Who feeds and is never fed, 
    The One Who is longed for, along with that which is with Him, and the One 
    Who is needed. He is Our Lord. Narrated by al-Bukhaari (5458). 

    So if a person forgets to say Bismillaah when he starts to 
    eat, then he remembers it when he has finished eating, it is mustahabb for 
    him to say Bismillaah fi awwalihi wa aakhirihi (In the name of Allaah 
    at the beginning and the end) and then praise Allaah. Thus he will have 
    acted in accordance with both hadeeths, and obeyed the command of the 
    Prophet  (peace and blessings of Allaah be upon him). There is no 
    contradiction in saying both dhikrs after one has finished eating, and it 
    seems that there is nothing wrong with saying al-hamdu-lillaah before saying
    Bismillaah fi awwalihi wa aakhirihi (In the name of Allaah at the 
    beginning and the end), in sha Allaah, because the aim is to say both 
    dhikrs, the Tasmiyah (saying Bismillaah) and praising Allaah, so it does not 
    matter which of them one starts with. 

    And Allaah knows best.