Ibn Majah

Benefit:
The situation mentioned in the hadith is different from eating or drinking out of forgetfulness.
Because they did not eat or drink forgetfully, but rather intentionally broke their fast, thinking (mistakenly) that the time for breaking the fast had arrived.
Even though, due to a misunderstanding, they broke the fast before its proper time.
On account of this misunderstanding, they are not sinful, but the fast has certainly become deficient.
There is a difference of opinion among the scholars regarding making up (qada) such a fast.
However, according to the majority of scholars, it is obligatory to make up the fast that was broken in this manner.
For details, see: (Fath al-Bari: 4/255)

Hadith Commentary: Upon this, there is consensus among the four Imams (a’immah arba‘ah) that in such a situation, making up (qada) the fast is obligatory, and there is no expiation (kaffarah). In addition, it is also necessary that until sunset, one must abstain (imsak), meaning one should not eat or drink anything.

Qastallani has narrated from some Hanbalis that if a person, thinking that night has fallen, breaks the fast (iftar), and then it becomes clear that it was still day, then making up (qada) is not obligatory upon him. However, this opinion is not correct.

I say: It is narrated from Umar (radi Allahu anhu) that in such a case, there is also no obligation to make up (qada), and the same is narrated from Mujahid and Hasan.

Hafiz said: There is also a narration from Imam Ahmad (rahimahullah) to this effect, and Ibn Khuzaymah has chosen this view, and the suspended narration (ta‘liq) of Ma‘mar has been connected (wasl) by ‘Abd bin Humaid.

This narration is contrary to the first narration, and perhaps at first Hisham was uncertain about it, then later became certain that he did make up (qada). And Abu Usamah may have narrated from him after he became certain about making up (qada); in this case, there would be no contradiction.

Ibn Khuzaymah said: Hisham did not mention the chain of transmission (isnad) for the statement about making up (qada), therefore, in my view, the opinion that there is no obligation to make up (qada) is preferable. And Ibn Abi Shaybah has narrated from Umar (radi Allahu anhu) that we did not make up (qada), nor did we consider ourselves sinful, and ‘Abd al-Razzaq and Sa‘id bin Mansur have narrated from him that making up (qada) is necessary.

Hafiz said: The summary of the discussion is that this issue is a matter of disagreement.

(Wahidi)

The apparent meaning of the hadith is that making up (qada) is obligatory, and Allah knows best.

Hadith Commentary:

(1)
If, after breaking the fast, the sun appears, what is the ruling regarding that fast? There is a difference of opinion among the early scholars on this matter. Imam Bukhari rahimahullah, in view of this difference, did not give a decisive ruling; rather, after narrating the report, he mentioned two different answers from Hisham.

According to us, the ruling regarding such a fast is that nothing should be consumed until the sun sets, and afterwards, the fast should be made up (qada). However, there is no expiation (kaffarah) or the like required for it.

There are two different narrations from Umar radi Allahu anhu regarding this:

Khalid bin Aslam narrates that Umar broke his fast on a cloudy day in Ramadan, and later the sun appeared. He said: Whoever has broken his fast should make it up later.

Zayd bin Wahb narrates that Umar radi Allahu anhu said: What fault is ours in this? We do not need to make up the fast as qada.

(Al-Sunan al-Kubra lil-Bayhaqi: 4/217)

Imam Bayhaqi rahimahullah, in view of the various narrations, declared the narration of Zayd bin Wahb to be incorrect because he opposed the majority. Then he referenced the narration of Suhayb, who ordered making up the fast later.

(Al-Sunan al-Kubra lil-Bayhaqi: 4/218)

(2)
Hafiz Ibn Hajar rahimahullah, supporting the view of making up the fast (qada), said:

If, due to a cloudy sky, the moon is not sighted and people do not fast, but later it becomes known that the moon had been sighted, yet the people did not fast, then they must make up that fast later. Similarly, in the case where the sun appears after breaking the fast, it is also necessary to make up the fast (qada).

(Fath al-Bari: 4/255)

Benefits and Issues:
There is a difference of opinion among the scholars regarding the making up (qada) of such a fast; however, according to the majority of scholars, it is obligatory to make up the fast that was broken in this manner.
(For details, see: Fath al-Bari: 4/255)