1. One should recite any of the following duaas before eating:
بِسْمِ اللهِ
In the name of Allah Ta’ala
بِسْمِ اللهِ وَ بَرَكَةِ اللهِ
In the name of Allah Ta’ala, and with the blessings of Allah Ta’ala.
عن بن عباس رضي الله عنهما أن النبي صلى الله عليه وسلم وأبا بكر وعمر رضي الله عنهما أتوا بيت أبي أيوب فلما أكلوا وشبعوا قال النبي صلى الله عليه وسلم خبز ولحم وتمر وبسر ورطب إذا أصبتم مثل هذا فضربتم بأيديكم فكلوا بِسْمِ اللهِ وَبَرَكَةِ اللهِ (مستدرك حاكم رقم 7084)
Hadhrat ibn Abbaas (Radhiallahu Anhuma) reports that on one occasion Rasulullah (Sallallahu Alaihi Wasallam), Hadhrat Abu Bakr and Hadhrat Umar (Radhiallahu Anhuma) went to the house of Hadhrat Abu Ayyoob (Radhiallahu Anhu). After they ate till they were satisfied, Rasulullah (Sallallahu Alaihi Wasallam) said: “When you acquire such food such as bread, meat, dry dates, semi-ripe dates and fresh dates, and you intend relishing such food, then remember to commence the meal by taking the name of Allah Ta’ala by saying:
بِسْمِ اللهِ وَ بَرَكَةِ اللهِ
In the name of Allah Ta’ala, and with the blessings of Allah Ta’ala.
2. Recite the duaa audibly (where it is possible) as a reminder to others.
3. If one forgets to recite the duaa in the beginning then one should recite the following duaa when one remembers:
بِسْمِ اللهِ أَوَّلَهُ وَ آخِرَهُ
(I commence) in the name of Allah Ta’ala from the beginning till the end.
عن عائشة قالت : قال رسول الله صلى الله عليه و سلم إذا أكل أحدكم طعاما فليقل بسم الله فإن نسي في أوله فليقل بسم الله في أوله وآخره (ترمذي رقم 1858)
Hadhrat Aaisha (Radhiallahu Anha) reports that Rasulullah (Sallallahu Alaihi Wasallam) said: “When you commence eating, then take the name of Allah Ta’ala by saying:
بسم الله
If however one forgets to recite it in the beginning of his meal, then he should recite:
بِسْمِ اللهِ فِي أَوَّلِهِ وَ آخِرِهِ
Or
بِسْمِ اللهِ أَوَّلَهُ وَ آخِرَهُ
عن أمية بن مخشى و كان من أصحاب النبي صلى الله عليه و سلم سمعته يقول : إن رجلا كان يأكل و النبي صلى الله عليه و سلم ينظر فلم يسم الله حتى كان في آخر طعامه فقال : بسم الله أوله و آخره فقال النبي صلى الله عليه و سلم : ما زال الشيطان يأكل معه حتى سمى فما بقي في بطنه شيء إلا قاءه (مستدرك للحاكم رقم 7089)
Hadhrat Umayyah (Radhiallahu Anhu) reports that on one occasion a man was seated with Rasulullah (Sallallahu Alaihi Wasallam) at the time of meals. The man did not remember to take the name of Allah Ta’ala until when he was about finishing the meal, he said:
بِسمِ اللهِ أَوَّلَهُ وَ آخِرَهُ
At that juncture Rasulullah (Sallallahu Alaihi Wasallam) exclaimed: "Shaytaan continued eating with this person until he took the name of Allah Ta’ala. (No sooner did he take the name of Allah Ta’ala), Shaytaan vomited all that he had consumed."