Do You Have to Recite Bismillah Before Every Surah?
Question

Must he say "Bismillahi rahman nirahim" quietly after finishing Al-Fatihah in order to begin the surah he will recite? What if he begins reciting in the middle of a surah?
Praise be to Allah.Reciting the Basmalah (i.e., the phrase “Bismillah ir-Rahman ir-Rahim (in the name of Allah, the most Gracious, the Most Merciful)” in prayer is encouraged not obligatory. 
It is recommended to recite the Basmalah if you are going to recite a Surah from the beginning, so the worshipper says it before Al-Fatihah . With regard to the Surah after Al-Fatihah, if he is reciting it from the beginning of the Surah, then he should say the Basmalah, apart from Surat At-Tawbah , because the Basmalah is not recited at the beginning of it. If he is reciting from the middle of a Surah , then it is not recommended to recite the Basmalah. 
The Standing Committee said: 
“The sound Sunnah indicates that the Prophet (peace and blessings of Allah be upon him) recited the Basmalah in prayer before Al-Fatihah and before other Surahs, apart from Surat At-Tawbah, but he did not recite it out loud in the prayers in which he recited Quran out loud.” (Fatawa Al-Lajnah Ad-Da’imah, 6/378) 
They also said: 
It is prescribed to recite the Basmalah in every Rak`ah before Al-Fatihah and before every Surah apart from Surah Bara’ah (i.e., Surah At-Tawbah).” (Fatawa Al-Lajnah Ad-Da’imah, 6/378) 
And they said: 
“If (the worshipper) is going to recite a Surah after Al-Fatihah, he should recite the Basmalah silently beforehand. But if he is going to recite a brief passage from the middle or end of a Surah, then it is not prescribed for him to recite the Basmalah.” (Fatawa Al-Lajnah Ad-Da’imah, 6/380)
And Allah knows best.