Hadith question

I have read a Hadith from somewhere that says that if someone reads Surah Ikhlaas 10 times after Fajr or Zuhr salah, then that person won't commit a sin on that day even if shaytan tries to make him sin. My two questions regarding this are: 1. Does this mean it's impossible for this person to sin? What if right after he reads it 10 times after fajr or zuhr salaah, he curses or watches zina (not saying this should be done)? Since the hadith says this, then does this mean it's impossible for him to curse or watch TV which is a sin in Islam? 2. Is this hadith even authentic, and can you please send me the link to the source of this hadith?