Qudamah (may Allah be pleased with him) says: When I used to come to Uthman bin Affan (may Allah be pleased with him) to receive my salary, he would ask me: "Is zakat obligatory on the wealth you possess?" If I said yes, he would deduct zakat from my salary, and if I said no, he would give me my salary.
Hadith Referenceمسند الإمام الشافعي / كتاب الزكاة / 693
Hadith Takhrijاسناده صحيح : اخرجه البيهقي في المعرفة السنن والآثار (2276) ۔ وعبدالرزاق (7029)۔