It is narrated from Hazrat Uqbah bin Aamir (may Allah be pleased with him) that once I submitted in the presence of the Messenger of Allah, "O Messenger of Allah! (peace and blessings be upon him) Is this virtue unique to Surah Al-Hajj in the entire Qur'an that it contains two prostrations?" The Prophet (peace and blessings be upon him) replied, "Yes! And whoever does not perform both prostrations, it is as if he has not recited this Surah at all."
Hadith Referenceمسند احمد / مسند الشاميين / 17364
Hadith Gradingحکم دارالسلام:حسن بطرقه وشواهده دون قوله: «فمن لم يسجدهما فلا يقرأهما» ، وهذا الإسناد ضعيف، حديث مشرح بن هاعان عن عقبة خاصة مقال