From Sahih Muslim (Hadith 5601):
Samura b. Jundub reported:The Messenger of Allah (peace and blessings of Allah be upon him) said "The dearest phrases to Allah are four: Subhan Allah (Hallowed be Allah), Al-Hamdulillah (Praise be to Allah), La ilaha illa-Allah (There is no deity but Allah), Allahu Akbar (Allah is Greater). There is no harm for you in which of them begin with (while remembering Allah). And do not give these names to your servants: Yasar and Rabah and Najih and Aflah
Reference: Muslim 5601