Translation:Shulchan Aruch/Orach Chaim/49
49: That one can recite the reading of Shema by heart.
1 Although halacha states that you are not permitted to read by heart portions of the written Torah, all those sections that people commonly know by heart, e.g. Krias Shema and Birkas Kohanim and Parshas HaTamid and so on, are permitted.