It is interesting that the founding and well known scholars of the Deobandi and Barelvi movements who have influence in the Indian Subcontinent, home to over a half of the Muslim Ummah have clearly stated this as the correct view regarding the sighting of the moon in their Fatawa. It is unfortunate that today that many who claim to follow them ignore following this Shariah rule.
The co-founder of Dar al-Uloom Deoband, Maulana Rasheed Ahmad Gangohi said: “If the people of Calcutta sighted the moon in Friday, whereas it was sighted in Makkah on Thursday itself, but the people of Calcutta did not know of it (the sighting on Thursday); then whenever they come to know of this, it will be obligatory for them to celebrate eid with the people of Makkah and make up (Qada’) for the first fasting.” [Maulana Rasheed Ahmad Gangohi, Sharh Tirmizi (Explanation of Tirmizi), Kaukab un Durri, pg 336, Urdu edition]
“Wherever the sighting is confirmed, however far off it may be, even if it were to be thousands of miles; the people of this place will have to abide by that.” [Fatawa Dar ul Uloom Deoband, Vol. 6 page 380, Urdu edition]
“Question: There has been some dispute in Amritsar etc. regarding sighting of moon for Ramdhan and Eid ul fitr. So should we the residents of Mandla (CP), which is located very far off, follow that sighting or not?
Answer: In the maslak of Hanafiyyah, there is no consideration of Ikhtilaf al Matale’ (difference in sighting); the sighting of the people of east is binding upon the people of the west and vice versa. This is also demanded by the hadith (soomoo li ru iyatihi we aftaroo li ru iyatihi) “Fast when it is sighted and stop fasting when it is sighted”, because the address ‘soomoo’ and ‘aftaroo’ is ‘aam (general) and for everyone. In conclusion, when sighting is confirmed in whichever place, everyone is supposed to start his fast and break it in accordance with it, i.e when the sighting is confirmed.” [Fatawa Dar ul Uloom Deoband, Vol 6 page 385 & 386, Urdu edition]
“Irrespective of how far the news of sighting came from, it is to be relied upon. For instance if the people of Burma did not sight the moon, and a person from Bombay testifies to them of having sighted the moon; it will be incumbent upon the people of Burma to make up for the (first) fasting i.e. Qada’.” [Mufti Kifayatullah, Ta’leem ul Islam, vol. 4, section sighting of moon: Urdu edition]
“When the moon is sighted in one place it is not just for that region but for the entire world.” [Maulana Amjad Ali, Bahar e Sharee’at, Vol 2 page 108, Urdu edition]
The founder of the Barlevi's said: “In the correct and authentic mazhab of our Imams, with regard to the sighting of moon for Ramdhan and eid, distance of the place of sighting is of no consideration. The sighting of the east is binding upon west and vice versa i.e. the sighting of west is similarly binding on east.” [Maulana Ahmad Raza Khan, Fatawa Rizwi; Vol 4 page 568, Urdu edition]
For further information including the evidences for this shariah rule see: The obligation of beginning of Ramadhan when the moon is sighted in any country