Yahya bin Sa'id (may Allah have mercy on him) narrates from his father that Umar bin al-Khattab (may Allah be pleased with him) said to Abdullah bin al-Arqam (may Allah be pleased with him): Distribute the treasury of the Muslims once every month; distribute it once every Friday; distribute it once every day. A man from the people said: O Commander of the Faithful! If only you would keep some remainder in the wealth of the Muslims, to have it ready for a calamity or an emergency. Umar (may Allah be pleased with him) said to the man who had said this: Satan has spoken on your tongue. Allah has taught me the argument against it and protected me from its evil. I will prepare for it what the Messenger of Allah (peace and blessings be upon him) prepared for it, namely obedience to Allah and His Messenger (peace and blessings be upon him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 13032