Musnad Ahmad 799:49

Muhammad ibn Ja‘far narrated to us, Shu‘bah narrated to us, from Salamah ibn Kuhayl, from Hilal ibn Yasaf, from Samurah, from the Prophet, peace and blessings of Allah be upon him, who said: "If I narrate a hadith to you, do not add anything to me." And he said: "Four are among the best of speech, and they are from the Quran; it does not harm you with which of them you begin: *Subhan Allah* (Glory be to Allah), *al-hamdulillah* (Praise be to Allah), *la ilaha illa Allah* (There is no god but Allah), and *Allahu akbar* (Allah is the Greatest)." Then he said: "Do not name your servant Aflah, nor Najih, nor Rabah, nor Yasar."