Reciting At-Tahiyyaat instead of Surah Faatiha

Q: Salaah-134: Will Sajdah Sahw be necessary if one recited At-Tahiyyaat instead of Surah Faatiha or Surah Faatiha instead of At-Tahiyyaat?

Answer: Sajdah Sahw will be necessary in both instances because a Waajib (compulsory) act has been omitted. And Allaah knows best what is most correct.

Fatawa Rahimiyyah vol.2