Musannaf Ibn Abi Shayba 3:1867

Hushaym narrated to us, from Shu'bah, from 'Asim, from Zirr, who said: The *'Aza'im* (obligatory/firm) prostrations are: *Alif Lam Mim Tanzil* (Surah As-Sajdah), *Ha Mim Tanzil* (Surah Fussilat), *An-Najm*, and *Iqra' bismi Rabbika alladhi khalaq* (Surah Al-'Alaq).