Hazrat Hanzala narrates that once during Ramadan, I was with Hazrat Umar. Something to drink was presented to him. Some people, thinking that the sun had set, drank it. Then the muezzin climbed up and announced, "O Commander of the Faithful! By Allah, the sun has not yet set." Hazrat Umar said, "May Allah protect us from your evil." He said this two or three times. Then, addressing the people, he said, "Whoever has broken the fast before its time today should fast one day in its place, and whoever has not broken the fast should wait for sunset."

This incident is narrated through another chain as well. However, in it there is this addition: We did not make you a guardian, We made you an inviter. We made our effort. In any case, making up for one day is easy.

Hazrat Bishr bin Qais says that in the case of breaking the fast before sunset, Hazrat Umar had ordered the people to make up (qada) for it.

Hazrat Asma states that during the Prophetic era (peace and blessings be upon him), on a cloudy day, people once broke their fast before sunset, but the sun set afterwards. Abu Usama says that he asked Hazrat Hisham whether they were ordered to make up (the fast). He replied, "What other option was there besides that?"

Hazrat Mujahid says that whoever breaks the fast before its time must make up the fast, because Allah Almighty says that { أَتِمُّوا الصِّیَامَ إلَی اللَّیْلِ }

The following hadith of Hazrat Umar is narrated through another chain of transmission.

Hasan says that if a person breaks his fast thinking that the sun has set, but then finds out that the sun has not yet set, his fast is still valid.

Hazrat Zaid bin Wahb narrates that a large vessel of food was brought from the house of Hazrat Hafsa, so people thought that the sun had set. That day it was cloudy, so the people broke their fast. After a while, the clouds cleared and the shining sun became visible. Upon this, Hazrat Umar said that we could not avoid sin.

Hazrat Qatan narrates that during the time of Hazrat Muawiyah, people broke their Ramadan fast before sunset, so Hazrat Muawiyah ordered them to make up (qada) the fast.

Hazrat Ibn Jurayj says that I asked Hazrat Ata: I broke my fast in Ramadan on a cloudy day thinking that the sun had set, but then the sun appeared. Should I make up this fast and not give expiation? He replied: Do just that.