Is it obligatory for a fasting person to make up the fast if he believed the sun had set and broke his fast, but it then turned out that the sun had not set?

Question:
May Allah reward you. The Honorable Shaykh says: You mentioned in your explanation of the book on fasting that if a fasting person breaks his fast and it then turns out that the sun had not set, he must make up the fast, because the default is that the day continues. The question is that a report was narrated in Sahih al-Bukhari from Fatimah (may Allah be pleased with her), who said: , and the Messenger of Allah (peace and blessings be upon him) did not order them to make up the fast. What is the explanation?

Answer:
The explanation is: Yes, making up the fast is obligatory, because it became clear to them that they ate during the day and did not complete the day, so they must make it up. When Hisham ibn 'Urwah, the narrator of the hadith, was asked whether it is obligatory, he said, "Is there any alternative to making it up?" The fact that the hadith does not mention that they made up the fast does not indicate that they did not make it up. The fact that it does not mention that they made it up, or that the Messenger ordered them to, does not indicate that they did not make it up. This is from the narration of Hisham ibn 'Urwah ibn al-Zubayr, who said, "Is there any alternative to making it up?" meaning that making it up is necessary, because it became clear that they did not complete the day with fasting, so they fast in its place. Yes.