What is the ruling on the fast of one who ate thinking that the night was still there?

Question:
Did he eat thinking that the night was still there, or did he eat thinking that the day was still there?

Answer:
The correct view is that he must make up the fast. If he ate in the morning thinking that the night was still there, and it then turned out that he ate during the day, he must make it up. This is the view of the majority of scholars. Likewise, if he thought that the sun had set, but it then turned out that it had not, the majority hold that he must make up the fast.
Q: Some people ask: What is the evidence?
A: The evidence is that it turned out that it was daytime, and it is obligatory for him to fast the entire day. It became clear that he ate during the day, and it was his duty not to be negligent. It was his duty to strive, exercise caution, and not hasten to break his fast or delay eating. Also, this is a door that, if opened, leads to great affliction and laxity.
Q: Did this happen once with the Messenger of Allah (peace and blessings be upon him)?
A: It is said that they made up the fast, and it is said that they did not make it up. This is from the hadith of Asma'. Some of the Salaf said that making up the fast is necessary. The majority hold that the fast must be made up, while some said that it does not need to be made up.