The Prophet ﷺ forbade mixing unripe dates with ripened dates when making a drink, and he forbade mixing raisins with dates, and he forbade making nabidh in earthenware jars.
حدثنا سفيان بن وكيع حدثنا جرير عن سليمان التيمي عن أبي نضرة
أن النبي ﷺ نهى عن البسر والتمر أن يخلط بينهما ونهى عن الزبيب والتمر أن يخلط بينهما ونهى عن الجرار أن ينبذ فيها
Reference: also narrated by Muslim, hadith 1987, from Sulayman Taymi with the same wording. On this subject, see also Ahmad 3/134, 140, 210, 251, and Jabir [previously mentioned at 1876], and Abu Qatada [Bukhari, hadith 5602, Muslim, hadith 1988, and Malik in Muwatta 2/844], and Ibn Abbas [Muslim, hadith 1997], and Umm Salama [Abu Dawud, hadith 3706, and Ahmad 6/292], and Mabad bin Kaab from his mother [Ahmad 6/18, and Humaydi, hadith 357].