"I said: 'O Messenger of Allah! Surah Al-Hajj has been esteemed by two prostrations?' He said: 'Yes, and whoever does not prostrate for them, he should not recite them.'" (Using translation from Tirmidhī 578)
قُلْتُ يَا رَسُولَ اللهِ أَفُضِّلَتْ سُورَةُ الْحَجِّ عَلَى الْقُرْآنِ بِأَنْ جُعِلَ فِيهَا سَجْدَتَانِ؟ فَقَالَ نَعَمْ وَمَنْ لَمْ يَسْجُدْهُمَا فَلَا يَقْرَأْهُمَا