This excerpt is taken from Sheikh Muhammad Farooq's book Issues of the Two Eids.
Will the Entire Muslim Ummah Celebrate Eid on the Same Day?
There is considerable disagreement on whether the entire Muslim Ummah will celebrate the two Eid festivals on the same day or whether the people of each region, whose moon sightings and observations differ, will celebrate their festivals according to their own moon calculations. The prevailing view on this issue is that the people of each region will hold the Eid celebrations according to their own moon calculations.
The authenticity and reasonableness of this issue are supported by the following arguments.
Argument Number 1:
It is an established fact that the Islamic months begin with the sighting of the moon on the 29th day or after completing 30 days of the month, and the moon's position and the sky vary in every region. Therefore, the people of each area will determine the Eid days and Ramadan based on their own moon sighting.
It is narrated from Abdullah bin Umar (may Allah be pleased with them) that the Prophet (peace be upon him) mentioned Ramadan and said:
لا تصوموا حتى تروه، ولا تفطروا حتى تروه، فإن أغمي عليكم فاقدروا له
"Do not fast until you see the crescent of Ramadan, and do not break your fast until you see the crescent of Eid al-Fitr. If the sky is cloudy, then estimate the month by counting."
Reference: Sahih Bukhari, Book of Fasting, Chapter: The Prophet's Saying: When you see the crescent, fast: 1906 - Sahih Muslim, Book of Fasting, Chapter: The obligation of fasting Ramadan upon seeing the crescent: 1080 - Sunan Nasai: 2123, Musnad Ahmad: 63/2 - Sahih Ibn Hibban: 3445
It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace be upon him) said:
صوموا لرؤيته: وأفطروا لرؤيته، فإن غمى عليكم فعدوا ثلاثين
"Fast when you see the crescent, and break your fast when you see the crescent, and if the sky is cloudy for you, then count thirty days."
Reference: Musnad Ahmad: 430/2 - Sahih Bukhari: 1909, Muslim: 1081, Sunan Nasai: 2120
Fiqh al-Hadith: .
These ahadith are clear evidence that there are two ways to determine Ramadan and Eid al-Fitr:
➊ After completing twenty-nine days of Sha'ban or Ramadan, the moon is sighted.
➋ If the moon is not sighted on the twenty-ninth day, then thirty days of the month are completed, and it is established that the sky of each region is different; therefore, this ruling is specific to each region whose moon sighting is the same, as proven by the following narration.
➌ Qareeb, may Allah have mercy on him, narrates:
أن أم الفضل بنت الحارث بعثته إلى معاوية بالشام قال: فقدمت الشام، فقضيت حاجتها، واستهل على رمضان وأنا بالشام، فرأيت الهلال ليلة الجمعة ثم قدمت المدينة فى آخر الشهر، فسألني عبد الله بن عباس رضى الله عنهما، ثم ذكر الهلال فقال: أنت رأيته فقلت: نعم، ورآه الناس، وصاموا وصام معاوية فقال: لكنا رأينا ليلة السبت، فلا نزال نصوم حتى نكمل ثلاثين، اونراه فقلت: اولا تكتفي برؤية معاوية و صيامه؟ فقال: لا ، هكذا أمرنا رسول الله صلى الله عليه وسلم
Umm Fadl bint Harith, may Allah be pleased with her, sent him to Sham (Syria) for some purpose to Muawiyah, may Allah be pleased with him. He said: I came to Sham, completed her task, and while I was still in Sham, the moon of Ramadan was sighted. I saw the moon on the night of Friday. Then, at the end of the month, I returned to Madinah, where Abdullah ibn Abbas, may Allah be pleased with both of them, asked me about the situation. Later, when the topic of the Ramadan crescent arose, he asked: When did you see the moon of Ramadan? I replied, we saw the moon of Ramadan on the night of Friday. He asked: Did you see the moon yourself? I said: Yes! I and others saw it, and based on that sighting, everyone including Muawiyah, may Allah be pleased with him, fasted. Ibn Abbas, may Allah be pleased with both of them, said: But we saw the Ramadan crescent on the night of Saturday, so we will fast continuously until we complete thirty days or see the moon.
I asked: Is Muawiyah’s moon sighting and fasting not sufficient for you? Hearing this, he said: No! Rather, the Messenger of Allah, peace and blessings be upon him, commanded us to fast by either sighting the moon or completing the count of the month, and to arrange Eid al-Fitr accordingly.
Reference: Muslim, Book of Fasting, Chapter on the fact that each town has its own sighting: 1087 - Abu Dawood, Book of Fasting, Chapter on if the crescent is sighted in a town: 2332 - Jami' Tirmidhi, Book of Fasting, Chapter on what has come about each town having its own sighting: 693 - Sunan Nasa'i: 2113 - Musnad Ahmad: 306/1 - Sahih Ibn Khuzaymah 1916
Fiqh al-Hadith:
This hadith is a clear text that the people of every region whose moon sighting is the same will celebrate Eid al-Fitr after sighting the moon or completing the thirty days of Ramadan. The sighting of the moon in one region does not obligate all Muslims on earth to follow the people of that region.
