The Messenger of Allah ﷺ made the zakat of Fitr obligatory, a sa of dates or a sa of barley, upon every free person and slave, male and female, among the Muslims.
أن رسول الله ﷺ فرض زكاة الفطر صاعا من تمر، أو صاعا من شعير على كل حر أو عبد ذكر أو أنثى من المسلمين.
Malik narrated it in zakat (52) from Nafi, from Abdullah bin Umar, and mentioned it. Bukhari narrated it in zakat (1504), and Muslim in zakat (984), both of them through the route of Malik, with the same wording.Regarding his saying, "of the Muslims," some scholars said long ago that Malik alone added this phrase, without the other companions of Nafi.I say, rather two trustworthy narrators corroborated him. The first is Umar bin Nafi, from his father Nafi, and his hadith is found in Bukhari's Sahih (1503), where he said, "The Messenger of Allah ﷺ made Zakat al-Fitr obligatory, a saa of dates or a saa of barley, upon the slave and the free, the male and the female, the young and the old among the Muslims, and he commanded that it be paid before the people went out to the prayer."The second is Dahhak bin Uthman, from Nafi, and his hadith is found in Muslim (984:16), that the Messenger of Allah ﷺ made Zakat al-Fitr of Ramadan obligatory upon every soul among the Muslims, free or slave, man or woman, young or old, a saa of dates or a saa of barley.The fact that Ubaydullah, that is, the son of Umar bin Hafs bin Asim bin Umar bin Khattab, did not mention "of the Muslims" in his hadith from Nafi from Ibn Umar, his hadith being in Muslim (984:13), does not harm the position of those who added it, namely a group consisting of Malik, Umar bin Nafi, and Dahhak bin Uthman. Each of them is among the trustworthy and precise narrators, and they agreed upon this addition. Even if only one of them had reported it alone, it would still stand as valid proof, so how much more so when they have all agreed upon it together.Tirmidhi said (676), after narrating the hadith through the route of Malik from Nafi, from Ibn Umar, "The hadith of Ibn Umar is a hasan sahih hadith, and he added in it 'of the Muslims.'" He said, "The scholars have differed on this. Some of them said, if a man has slaves who are not Muslims, he does not pay the charity of Fitr on their behalf, and this is the view of Malik, Shafii, and Ahmad. Others said it is paid on their behalf even if they are not Muslims, and this is the view of Thawri, Ibn Mubarak, and Ishaq." End of quote.I say, perhaps these scholars were not aware of the addition "of the Muslims," thinking that Malik alone reported it and that Ubaydullah bin Umar had not mentioned it.