Sahih Muslim
The Book on General Behaviour (Kitab Al-Adab)
Book Number: 025 / Hadith Number: 5329
Samura b. Jundub reprted: The dearest words to Allah are four: Subhan Allah (Hallowed be Allah), Al-Hamdulillah (Praise be to Allah), Wa la ilaha illa-Allah (There is no god but Allah), Allah-o-Akbar (God is the Greatest). There is no harm for you in which order you begin (them while remembering Allah), and he also said: Do not give these names to your servants, Yasar and Rabah and Nafi and Najth.