Whoever intentionally vomits during the day of Ramadan, it is considered: if the vomit is mouthful, then his fast is invalidated whether the vomit returned by itself, or he caused the vomit to return, or the vomit came out and he did not return it nor did it return by itself, and it is not applicable to differentiate between returning and causing to return; because he has broken his fast merely by the exit of the vomit. However, if the vomit is less than a mouthful: it does not invalidate the fast whether the vomit returned by itself, or he caused the vomit to return, or the vomit came out and he did not return it nor did it return by itself, it does not invalidate the fast in all these cases; due to the lack of exit; because a mouthful has the ruling of being an exit, and anything less than that is not considered an exit; because it can be controlled. Refer to Al-Tabyin 1: 325-326, and Rad al-Muhtar 2: 111.