The Shaykh (Al-Mufid), may Allah سبحانه وتعالى have mercy on him, said: “Whoever thinks that the sun has set because of an intervening circumstance (arid) such as clouds or something else, so he breaks his fast, then it becomes clear that it had not set at that time, it is obligatory upon him to make it up.” What Shaykh, may Allah سبحانه وتعالى have mercy on him, mentioned is the narration of Samaah ibn Mihran in the narration of Muhammad ibn Yaqub from Samaah and Abu Basir, and no one other than the two of them narrated it (in the following hadith).