This ḥadīth, then, is evidence for the unanimous position of the Muslim community—save for a handful of late dissenters who appeared after the consensus had long been established—that the times for beginning the fast, ending it, and performing the rites of worship are to be determined by actual sighting whenever sighting is possible, not by the astronomical calculations adopted by non-Arab nations such as the Romans, Persians, Copts, and Indians, nor by the People of the Book, both Jews and Christians.
More than one scholar has transmitted that the two earlier communities of Scripture were likewise commanded to rely on sighting for their fasting and other acts of devotion, interpreting in that light the divine statement: “Fasting has been prescribed for you just as it was prescribed for those before you” (al-Baqarah 2:183). Yet the People of the Book altered what they had been given.
For this reason the Prophet—peace and blessings be upon him—forbade starting the fast of Ramadan a day or two early. The jurists explained that this prohibition is meant to prevent anything not originally part of the obligatory fast from being added to it, just as the People of the Book—specifically the Christians—lengthened their fast and placed it between winter