THE VERSE "BISMILLAHIR RAHMANIR RAHIM"
Whenever we recite a verse from the Holy Qur'án, we start with Bismilláh, i.e. Bismilláhir Rahmánir Rahím. The verse means, "In the Name of Alláh, the Most Beneficent, the most Merciful."
The verse appears 114 times in the Holy Qur’án. It appears at the head of all the Suras except for Súrah al-Bará'ah (Tawbah) where the Bismilláh is not recited.
This is for two reasons. The first is that it is believed that the Súrah is a continuation of the previous Súrah , al-Anfál.
Another reason may be that the Súrah contains very stern commandments against the idolaters and hypocrites and curses them.
In Súrah an-Naml (the Ant), the Bismilláh appears twice, once at the head of the Súrah , and once as verse 27:30:
"She (the queen Bilqís) said, "O’ chiefs, verily, an honourable letter has been delivered to me.
It is from Sulaymán, and it says, "In the name of Alláh, the Beneficent, the Merciful;
Do not exalt yourselves against me, and come to be as those who submit (themselves to Alláh)." (an-Naml, 27:29-31)
Tafsír
Imám Ja’far as Sádiq (A) has said about Bismilláh:
The "Ba" is derived from "Baha-alláh", the Splendour of Alláh.
The "Seen" is derived from "Saná-alláh", the Majesty of Alláh.
The "Meem" is derived from "Mulk-alláh" the Kingdom of Alláh.
"Allah" is the God of everything.
"Ar Rahman"is the One Who is Merciful to all His creation.
"Ar Rahim" is the One Who singles out those who believe in Him to receive the greatest share of His mercy.
The words Rahmán and Rahím are essentially from the same root word meaning mercy or grace. Yet in their application, they mean a different aspect of Alláh’s mercy.
He is Rahmán to all His creation, whether they be obedient to Him or disobedient.
He is Rahím to the faithful Muslims who do good and receive His mercy as a reward, both in this world and the next.
Is Bismillah part of the Suras of the Holy Qur'an
Merits of reciting Bismilláh
The Holy Prophet (S) has said that when a teacher teaching a child to recite the Holy Qur'án tells the child to recite "Bismilláhir-Rahmánir-Rahím", and the child recites it, Alláh will decree a clearance for the child, for his parents, and for the teacher, from hell. He also said that the verse is comprised of nineteen letters, the same number as the number of the keepers of the gates of hell; therefore, whoever pronounces it, Alláh will permit these letters to close the gates of hell against him.
To begin any good deed with the Bismilláh means that you are asking Alláh for His help in successfully completing the work. It also indicates your intention and reminds you that the work is undertaken solely for the pleasure of Alláh. In other words, if a task is undertaken without reciting Bismilláh, it may be completed, but it does not earn His pleasure.
References
Holy Qur’án, Tafsír of S V Mir Ahmed Ali
Ramadhan, Ahkam and Philosophy, Yasin T. al Jibouri