Question 208:  A brother asked me that if he swallowed that acid stuff which comes from the stomach, and when he swallowed it, he had an idea that it might break his fast but he wasnt sure…he has to give qadha but is that considered jahl taqseeri due to him not knowing for sure but he couldve avoided it by precaution and check if he felt it was maybe a fast breaker or is dhann sufficient to be jahl qasoori and one must have yaqeen that it breaks his fast for him to give kafarat, example, I swallow the acid liquid from my stomach with yaqeen it doesnt break my fast, then i find out, im fine but if i swallow it ,knowing theres a good chance that it might break my fast, isnt that unpardonable ignorance due to me being able to refrain from that and check cause i had an idea that it might break my fast. Generally what is the Rules on swallowing acid stuff from stomach while fasting?

Answer 208: If one who is fasting belches out something and it comes into the mouth, if he swallows it again, it will invalidate his fast no matter how little it is and he has to make up for it and also make kaffarah (either fast 60 days or feed 60 poor people the way mentioned in related books). Also, if what he has swallowed is something that is haram to eat, such as blood, he will have to do kaffarah jam’ (meaning that he has to both fast 60 days and feed 60 poor people).[1] All if this is if he swallowed it intentionally. None of what was mentioned applies if it was unintentional though and the fast is valid. Read More