Fasting: Intentionally Invalidating a Qadaʾ Fast After Zuhr
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1656
If after ẓuhr someone who is keeping a qaḍāʾ fast of the month of Ramadan intentionally does something that invalidates his fast, he must give one mudd of food to ten poor people, and if he cannot, he must fast for three days.