Musannaf Ibn Abi Shayba 27:218

Waki' narrated to us, from Thabit, from 'Umarah, from 'Abdullah ibn Ma'bad al-Zamani, who said: "Bismillahi al-Rahmani al-Rahim" was not revealed in any part of the Qur'an except in Surah al-Naml: "Indeed, it is from Solomon, and indeed, it is 'In the name of Allah, the Entirely Merciful, the Especially Merciful'."