Fiqh-us-Sunnah Volume 1, Purification and Prayer, Fiqh 1.121.

Section : Obligatory acts of prayer, Bismillah.

The scholars are agreed that the bismillah (the words “In the name of Allah, the Compassionate, the Merciful) is a verse in Surah al-Naml, but they differ over whether or not it constitutes a verse of every surah. There are three opinions on this point:

1. It is a verse of al-Fatihah and of every surah of the Qur’an. Therefore, it is to be recited with al-Fatihah during those prayers that are said aloud or quietly. The strongest support of this opinion comes from the hadith of Na’em al-Mujammir who said, “I prayed behind Abu Hurairah and he recited, ‘In the name of Allah…’ and then he recited al-Fatihah.” At the end of the hadith, he is quoted as saying, “By the One in whose Hand is my soul, I have done what resembles how we prayed with the Messenger of Allah.”

2. It is a verse by itself and was revealed to demarcate different surahs. It is allowed to recite it with al-Fatihah (in fact it is preferred), but it is not sunnah to recite it aloud. Anas said, “I prayed behind the Messenger of Allah, Abu Bakr, ‘Umar and ‘Uthman, and they did not recite it aloud.”

This hadith is related by an-Nasa’i, Ibn Hibban and at-Tahawi with a sahih chain according to the criterion of the two Sahihs.

3. It is not a verse of al-Fatihah or of any other surah. It is disliked to recite it aloud or quietly during the obligatory prayers, but not for the superogatory prayers. This opinion, however, is not strong.

Ibn al-Qayyim has reconciliated the first and second opinions by saying, “Sometimes the Prophet would recite it aloud, but most of the time he would say it quietly and not aloud.”