This research is concerned with studying the state's public finances from its revenues, which came in accordance with Islamic instructions, and which undoubtedly caused a great change in many pre-Islamic behavior and dealings. Public funds over flooded the Islamic state at the beginning of the era of Caliph Omar Ibn Al-Khattab until it was able to finance a system of giving, Accordingly, gifts were spent on Muslims as a result of conquests and spoils, one fifth of which was given to the treasury ( Bait al-mal ), and the conquerors got four fifths of it, Also, the new financial sources are from the zakat of those who entered Islam, As a tribute to the one who chose to remain on his religion, the tax of the land, it financed the treasury, and The expansion of the area of the open countries and the exchange and prosperity of trade play a role in feeding the treasury with tithes from the trade exchanged externally with non-Muslim countries and internally between Muslim cities.