Sahih Muslim
The Book Concerning the Use of Correct Words (Kitab Al-Alfaz min Al-Adab wa Ghairiha)
Book Number: 027 / Hadith Number: 5589
Abu Huraira reported from Allah's Messenger (may peace be upon him) various ahadith, one of which is this that he said: None of you should use the word al-karm for 'Inab, for karm (worthy of respect) is a Muslim person.