Abu Dawud
Prayer
Book Number: 002 / Hadith Number: 1491
Narated By Asma' daughter of Yazid : The Prophet (pbuh) said: Allah's Greatest Name is in these two verses: "And your diety is one diety; there is no diety but He, the Compasionate the Merciful," and the beginning of Surah Al 'Imran, A.L.M. Allah, there is no diety but He, the Living, the Eternal.