By giving Sadaka Fitr a beliver is demonstrating his gratitude of being able to complete all kinds of divine services during the whole month of Ramadan. The giver and acceptor of this Sadaka Fitr are both gaining benefits. As the giver Allah may grant him redemption and forgiveness due to the kindness he has done and as the acceptor certain of his needs are fulfilled. Though the beliver shall complete his Sadaka Fitr before eid prayer is performed.
Ibn Abbas said: “The Messenger of Allah (ﷺ) enjoined Zakatul-Fitr as a purification for the fasting person from idle talk and obscenities, and to feed the poor. Whoever pays it before the (Eid) prayer, it is an accepted Zakah, and whoever pays it after the prayer, it is (ordinary) charity.” (Ibn Majah, Zakat, 21)