Zakatul-fitr was ordained by the Wise Legislator for two reasons:

• to purify those who fasted, cleansing their fast from marring things such as indecent talk and minor sinning,
• to feed the poor Muslims so that they have enough provision during the Eid.

Ibn `Abbas (may Allah be pleased with him) reported:

"The Messenger of Allah (peace be upon him) ordained zakatul-fitr to purify the fasting person from indecent words or actions, and to provide food for the needy. It is accepted as zakah for the person who gives it before the Eid prayer; but it is a mere sadaqah for the one who gives it after the prayer."