Ibn Abi Su'ayr narrates from his father (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Pay a sa' of wheat on behalf of every male and female, on behalf of the young and the old, and on behalf of every free person and slave. As for the one who is wealthy, Allah will purify him; and as for the one who is poor, more will be returned to him than what he gives."
Sulayman bin Dawud narrates through Hammad that he (peace and blessings be upon him) said: "Young or old, wealthy or needy," and he also said: "Pay a sa' of wheat," or he said: "wheat, on behalf of every person."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7695