Answered by Shaykh Abu Usamah
I understand that it’s not permissible to hold any book of reference to help with namaz whilst doing Fard or Nafl salah, but is this the same for Sunnah and Witr salah also? What if one hasn’t learned any surahs apart from al-Fatiha or Qul huwala hu ahad, and subhana kulla huma wa bihamdika can we either repeat these, or recite other surahs in place of additional surahs that we DO know of by heart.
Al-Salam `alaykum
Holding a book and reciting from it will invalidate the prayer, be it Fard, Wajib, Sunna or Nafl. This is due to its constituting Amal Kathir (a great amount of action that renders the prayer invalid) and more so because it entails being prompted from a book.
You should simply recite those suras that you do know and continue with your efforts to learn more suras and include them in your salah.
(Radd al-Muhtar 1.672, Dar al-Fikr)