What is the virtue of Surat As-Saffat and Az-Zalzalah?

No authentic hadith has been reported regarding the virtue of Surat Al-Saffat, and whatever is narrated about its virtue is fabricated, by agreement of the people of knowledge. As for Surat Al-Zalzalah, a hadith has been reported concerning it: "If [Surat] Al-Zalzalah [is recited], it is equivalent to half of the Quran." This is a gharib (unfamiliar) hadith that the people of hadith knowledge have deemed weak. And Allah knows best.