Question
What is the way the obligation of Zakat al-Fitr is established?
Answer
It is obligatory in a broad sense during one's lifetime: such as zakat, vows, expiations, and similar matters according to the correct view; because the command to perform them is unrestricted by time, so the obligation only becomes limited at the end of life, similar to the command regarding zakat and other commands that are unrestricted by time. See: Bada'i al-Sana'i 2: 69.