Musannaf Ibn Abi Shayba 3:1973

'Abd al-A'la narrated to us, from Dawud—meaning Ibn Abi Iyas—from Ja'far, that Sa'id ibn Jubayr said: The *'aza'im* (obligatory/firm) prostrations are: *Alif Lam Mim Tanzil* (Surah as-Sajdah), *an-Najm*, and *Iqra' bismi Rabbika alladhi khalaq* (Surah al-'Alaq).