Fiqh-us-Sunnah Volume 3, Zakaat and Fasting, Fiqh 3.088.

Section : Who Must Pay Zakat ul-Fitr.

Zakat ul-fitr is incumbent on every free Muslim who possesses one sa’ of dates or barley which is not needed as a basic food for himself or his family for the duration of one day and night. Every free Muslim must pay zakat ul-fitr for himself, his wife, children, and servants.