Musnad Abu Ya'la al-Mawsili 155:89

Bishr ibn al-Walid al-Kindi narrated to us, Yahya ibn al-Ala’ al-Razi narrated to us, from Muhammad ibn ‘Amr ibn ‘Alqamah, from Abu Salamah, from Abu Hurayrah, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Do not call the grape 'al-karm' (the noble/generous), for indeed the 'karm' is the heart of the believer."