The Prophet ﷺ said, "Do not call grapes 'karm,' for karm is the heart of the believer."
عن النبي ﷺ قال: لا تقولوا: كرم؛ فإن الكرم قلب المؤمن.
Bukhari related it in the Book of Manners (6183), and Muslim related it in the Book of Wordings from Manners (7:2247), both through routes from Sufyan, from Zuhri, from Saeed bin Musayab, from Abu Hurairah, as mentioned. The wording given is that of Muslim. Muslim mentioned many of its routes and wordings. Abu Dawud related it (4974) through another route, adding, "But say instead, 'gardens of grapevines.'"The legal point of the hadith is that the Prophet ﷺ forbade calling the grapevine "karam," as the Arabs used to call it in the pre-Islamic era. This was because they used to make wine from it, and it was one of the finest kinds of wine to them, and so they named it "karam" (meaning noble or generous). The Prophet ﷺ therefore stripped this fine name from that vile drink and made it instead a description of the Muslim who avoids drinking it and restrains himself out of honor and dignity.