What is the difference between the appearance of dawn (Fajr) and the rising of dawn, and what are the ways to ascertain its appearance at present, and does the rising of dawn necessitate abstention (from food and drink for a fasting person), and what did Ibn Hazm mean by his statement, "and he is unable to make up for it"?

Ibn Hazm stated that whoever sees the dawn while eating or engaging in intercourse should immediately stop and complete their fast, with no need for a make-up fast. This is because Allah permitted eating, drinking, and intercourse until the dawn becomes clear. However, whoever eats or drinks while doubting the sunset is disobedient and has invalidated their fast, with no need for a make-up fast. If one engages in intercourse while doubting, expiation is required. Ibn Hazm does not consider a make-up fast obligatory except in the case of intentional vomiting. The majority of scholars, however, believe that a make-up fast is obligatory for anyone who eats, drinks, or engages in intercourse believing the sun has set or the dawn has not yet broken, and then it becomes clear otherwise. They cite the hadith of Asma bint Abi Bakr, Umar ibn al-Khattab, and Suhayb (may Allah be pleased with them) as evidence, and also because the verse stipulates the clarity of dawn.

Regarding doubt about sunset, Ibn Hazm holds that whoever eats or drinks while doubting the sunset is disobedient and has invalidated their fast, and cannot make it up. If one engages in intercourse, expiation is required. He believes that no make-up fast is due for such breaking of the fast, except in the case of intentional vomiting, as a text explicitly mentions this. In contrast, the majority of scholars believe that a make-up fast is obligatory for anyone who intentionally breaks their fast with any of the fasting nullifiers.