Abu Dawud Book 2, Hadith Number 1397.
Chapter : How many places are there in the quran where prostration is required.
Narated By Uqbah ibn Amir : I said to the Apostle of Allah (PBUH): Are there two prostrations in Surah al-Hajj? He replied: Yes; if anyone does not make two prostrations, he should not recite them.