Asma’ daughter of Yazid reported the Prophet as saying, “God’s greatest name is in these two verses, ‘And your God is one God; there is no god but He, the Compassionate, the Merciful’ [Qur'an, ii, 163.], and the beginning of Al 'Imran, ‘A.L.M. God, there is no god but He, the Living, the Eternal’ [Qur'an, iii. 1.]”
Tirmidhi, Abu Dawud, Ibn Majah and Darimi transmitted it.