What is the ruling on fasting for a person who suffers from excessive stomach acidity and has undergone surgery, and whose doctor advises him to eat every two hours? Is it permissible for him to break his fast?

If the doctor's advice to eat every two hours is merely a regulation, and not following it does not result in harm, unbearable hardship, or delayed recovery, then the father must fast and is not permitted to break his fast. However, if not following the doctor's advice results in harm, unbearable hardship during fasting, or delayed recovery, then the father is permitted to break his fast, as he is ill.

If his recovery from illness is hoped for, he must make up the days he missed after recovering. If his illness is not hoped to be cured, then he must feed a poor person for each day, and the make-up is waived for him.