Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates: Dates of zakat were brought to the Prophet (peace and blessings of Allah be upon him). Sayyiduna Imam Hasan bin Ali (may Allah be pleased with him) picked up one of those dates. He put it in his mouth, so the Prophet (peace and blessings of Allah be upon him) said: Spit it out, spit it out, zakat is not lawful for us.
Hadith Referenceصحیح ابن حبان / كتاب الزكاة / 3294
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح: ق.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرط الشيخين