“The Messenger of Allah, may Allah’s peace and blessings be upon him, prescribed zakāt al-fiṭr as a purification for the fasting person from idle talk and obscenity, and as food for the poor. Whoever gives it before the ‘Īd prayer, it is accepted as zakāt; and whoever gives it after the prayer, it is considered one of the voluntary charities.”

Narrated by Abū Dāwūd (No. 1609), Ibn Mājah (No. 1827), and al-Ḥākim in al-Mustadrak (No. 1488), from the ḥadīth of Ibn ‘Abbās, may Allah be pleased with them both.
Authenticated in Ṣaḥīḥ al-Jāmi‘ (No. 3570) and Irwā’ al-Ghalīl (No. 843).

Brief Explanation of the Hadith

Among the mercy of Allah, the Exalted, toward His servants is that He legislated zakāt al-fiṭr for them at the conclusion of Ramaḍān: as a purification and compensation for any deficiencies that may occur in the fast, and as a favor to the poor and needy, so that they may share in the joy of the Muslims.
And his statement: “The Messenger of Allah, may Allah’s peace and blessings be upon him, prescribed zakāt al-fiṭr” means that he made it obligatory and binding upon the Muslims.
It is called zakāt al-fiṭr because it is linked to the breaking of the fast in Ramaḍān. It is also said that it is called so because it is a purification for the body, unlike the usual zakāt, which is prescribed for wealth.
The ḥadīth clarifies the wisdom behind its legislation, which comprises two matters:
The first: “as a purification for the fasting person from idle talk and obscenity”—that is, it compensates for any deficiency in the fast caused by wrongful or improper speech, just as the two prostrations of forgetfulness compensate for deficiencies in prayer.
The second: “and as food for the poor”—that is, it is given to the needy on the day of ‘Īd, so that they may share in the joy of the Muslims and be spared from asking others on that day.
His statement: “Whoever gives it before the prayer, it is accepted as zakāt” indicates the most virtuous time for giving it, which is between the dawn (Fajr) and the ‘Īd prayer.
Some scholars have permitted giving it a day or two before ‘Īd, following the practice of the companions, may Allah be pleased with them. As for his statement, may Allah’s peace and blessings be upon him: “and whoever gives it after the prayer, it is considered one of the voluntary charities”—the meaning is that whoever delays it beyond its prescribed time does not fulfill zakāt al-fiṭr in its complete sense, but it counts as a voluntary charity, while the obligation to give it remains as a debt to be fulfilled.
The ḥadīth also indicates that zakāt al-fiṭr is to be distributed specifically to the poor and needy, and not to the other categories of zakāt al-māl (the general zakāt on wealth).