Musa bin Talhah (may Allah have mercy on him) says: We had the document of Mu'adh bin Jabal (may Allah be pleased with him) which the Messenger of Allah (peace and blessings be upon him) had given him: "That he should collect zakah from wheat, barley, raisins and dates."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7474