The Book Concerning the Use of Correct Words (Kitab Al-Alfaz min Al-Adab wa Ghairiha)
Muslim :: Book 27 : Hadith 5591
Abu Huraira reported Allah's Messenger (may peace be upon him) as saying: None of you should say: My bondman and my slave-girl, for all of you are the bondmen of Allah, and all your women are the slave-girls of Allah; but say: My servant, my girl, and my young man and my young girl.