Hadith 1740
Abu Hurairah (May Allah be pleased with him) said:
عن أبي هريرة رضي الله عنه قال: قال رسول الله صلى الله عليه وسلم : "لا تسموا العنب الكَرْم، فإن الكَرْم المسلم" ((متفق عليه)). ((وهذا لفظ مسلم)). وفي رواية: "فإنما الكرم قلب المؤمن" وفي رواية للبخاري ومسلم: "يقولون الكرم، إنما الكرم قلب المؤمن".
The Messenger of Allah (ﷺ) said, "None of you should use the word Al-Karm for grapes, for Al-Karm is a Muslim (worthy of respect)." [Al- Bukhari and Muslim] Another narration is: "Verily, Al-Karm is the heart of a true believer." Another narration is: "People have named grapes as Al-Karm; verily, only the heart of a believer is Al-Karm."
In plain words
The Prophet redirected the honourable word al-karm away from the grapevine, the source of wine, saying it truly belongs to the heart of a believer. True nobility lies in faith, not a vine.
Reference : Riyad as-Salihin 1740 In-book reference : Book 17, Hadith 230