Hadith 5:586
Sahl ibn Yusuf narrated to us, from ‘Amr, from al-Hasan, that he used to consider Zakat al-Fitr (Sadaqat Ramadan) obligatory upon the Mukatab (an enslaved person who has entered into a contract of manumission).
حدثنا سهل بن يوسف عن عمرو عن الحسن أنه كان يرى عن المكاتب صدقة رمضان