Fasting is an obligation enjoined by Allah, the Almighty, at a fixed time in the year, and cannot be performed at any other time. Therefore, the Muslims should know the rulings related to the start and end of Ramadan in order to perform this act of worship as prescribed.

How the Start of Ramadan is Proven:

The start of Ramadan is proven by one of two matters:

First: Sighting the crescent of Ramadan, which is demonstrated by Allah’s saying: “So whoever sights [the crescent of] the month, let him fast it.” (Quran 2: 185) The Messenger of Allah () said, “Fast when you see the new moon, and break it on sighting it (the new moon).” (Reported by Al-Bukhari and Muslim)

The start of Ramadan is proven if the crescent is sighted by an adult Muslim of sound mind and reliable character whose experience and honesty are trusted. Accordingly, people must start to fast.

Second: The start of Ramadan is also proven when Sha‘ban is thirty days, because the maximum number of days of the lunar month is thirty. Al-Bukhari and Muslim reported from Ibn Omar (may Allah be pleased with them) that the Messenger of Allah () said, “The month is thus and thus and thus,” namely thirty days. Then (holding out his ten fingers twice and then nine fingers), he said, “It may be thus and thus and thus,” namely twenty nine days. He meant once thirty days and once twenty nine days.

If Sha‘ban is thirty days, this means that Ramadan has undoubtedly started, as the Prophet () said, “Start fasting on seeing the crescent (of Ramadan), and give up fasting on seeing the crescent (of Shawwal), and if the sky is overcast (and you cannot see it), complete thirty days of Sha‘ban." (Reported by Al-Bukhari and Muslim)

If people try to see the crescent but have not sighted it, they should consider Sha‘ban thirty days and not fast on the 30^th day of Sha‘ban as the first day of Ramadan because the start of the month has not been proven. This is in accordance with the correct opinion maintained by the scholars.

The 30^th day of Sha‘ban is known as the Day of Doubt, where people are not permitted to fast, according to the saying of Ammar ibn Yasir (may Allah be pleased with them), “He who keeps fast on this day disobeys Abul Qasim (i.e. the Prophet).” (Reported by Abu Dawood)

It was authentically reported that the Prophet () forbade fasting on the Day of Doubt. It was reported in the Two Sahih Books of Hadith (Al-Bukhari and Muslim) that the Prophet () said, “Do not fast a day or two days ahead of Ramadan. But if anyone is in the habit of fasting certain days (which coincided with these days), let him fast on that day (or days).” This is in addition to the Prophet’s saying in the previously-mentioned Hadith, “Start fasting on seeing the crescent (of Ramadan), and give up fasting on seeing the crescent (of Shawwal), and if the sky is overcast (and you cannot see it), complete thirty days of Sha‘ban.”

The Hadith clearly indicates that the fasting of Ramadan depends on the sight of the crescent; if the crescent is not seen, people should consider Sha‘ban thirty days. Therefore, it is preferable that people try to see the crescent of Ramadan during the 30^th night of Sha‘ban, but this is not obligatory for every Muslim, as it is a collective duty, if done by some people, the rest of people are absolved of the responsibility.

To sum up, if the start of Ramadan is proven by either of the two previously-mentioned ways, people must fast; otherwise, they should not start fasting. The end of Ramadan is proven by either of the two ways mentioned in the Hadith. However, the crescent of Shawwal is proven by two persons, unlike sighting the crescent of Ramadan, which is proven by one person who fulfills the conditions set for the person who sights the crescent. The reason for the difference between sighting the crescent of Ramadan and that of Shawwal is that ending an act of worship requires taking more precautions than starting it.

One of the controversial matters discussed by former and later Sharia scholars is: if the crescent of Ramadan is seen in one Islamic country, should the rest of the Islamic countries act according to the crescent-sighting in this country? Scholars have numerous sayings in this regard, but there is not enough room to mention them.

The preponderant opinion supported by evidence from the Quran, the Sunnah, and logic is the view related to the nonlocal sighting of the new moon, as the moon rises at different times in different places. Therefore, each place has its own sighting of the moon, but if the sighting of the moon does not differ at different places, the place in which the moon is not seen should follow the other places and act according to this sighting. This is in accordance with Allah’s saying: “So whoever sights [the crescent of] the month, let him fast it.” (Quran 2: 185) The Prophet () also said, “Start fasting on seeing the crescent (of Ramadan), and give up fasting on seeing the crescent (of Shawwal).” (Reported by Al-Bukhari and Muslim)

It is not obligatory for every Muslim to sight the moon, but the sighting of the moon by a trustworthy Muslim of a reliable character suffices, and the rest of the Muslims should act according to this crescent-sighting as long as the moonrise does not differ. This is in accordance with the preponderant opinion maintained by the Muslim scholars. One of the theoretical evidences is that monthly timings can be measured in the manner daily timings are measured; as long as the emergence of dawn and sunset differs in various countries, people start fasting and break their fast at different times. The same idea applies to the start and end of the month. As we support the opinion that sunrise and sunset differ in the daily timing from one county to another, we should also support the opinion that monthly timings differ from one place to another.

This is the summary of what scholars have said about this issue. Allah, the Almighty, knows best.