What is the authenticity of the hadith narrated by Abu Hurairah describing "the pious, the pure, the hidden, the innocent," and is it permissible to recite Surat As-Sajdah in prayer with the intention of protecting the feet from the torment of the grave, by analogy with what is stated regarding the virtue of Surat Al-Mulk, and is that considered an innovation (bid'ah)?

The aforementioned hadith regarding the characteristics of the "pure, hidden ones" (al-asfiya al-akhfiya) is very weak and denounced, and its chain of transmission (sanad) is weak, obscure, and断裂 (disconnected), containing unknown narrators. There is no basis for what is mentioned about reciting Surah As-Sajdah and Surah Al-Mulk to protect the feet from the punishment of the grave; rather, it is an innovation (bid'ah). It is hoped that for whoever consistently recites Surah Al-Mulk, Allah will save them from the punishment of the grave through its blessings. The hadith about the intercession of two surahs like two wings refers to Surah Al-Baqarah and Surah Al 'Imran, not Surah As-Sajdah and Surah Al-Mulk, as stated in Sahih Muslim.