Ramadhan fasting

If it is doubtful whether it is the last day of Sha'ban or the first of Ramadhan. and observes a qadha or a Mustahab fast or some other fast on that day. and later comes to know the same day that it is the first of Ramadhan, then he should convert the intention to the Ramadhan fast.

If a person eats or drinks something intentionally, while being conscious of fasting, his fast becomes void, irrespective of whether the thing which he ate or drank was usually eaten or drunk (for example bread with water) or not (for example dust) and whether it is more or less; even if a person, who is fasting, takes the tooth brush out of his mouth and then puts it back into his mouth, swallowing its liquid, his fast will be void, unless the moisture in the tooth brush mixes up with the saliva in such a way that it may no longer be called an external wetness.

Should throw the food out of his mouth, and if he swallows it intentionally, his fast is void, and it also becomes obligatory on him to give Kaffarah.

If a person who is fasting eats or drinks something forgetfully, his fast does not become invalid.