Sayyiduna Ibn Mas'ud (may Allah be pleased with him) said: "Whoever recites Surah al-A'raf, Surah al-Najm, or 'Read in the name of your Lord who created', and wishes to bow at the end of them, let him bow; the prostration of the bowing will suffice for him. And if he prostrates, let him add another surah after it."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 8701