Why are the Muslims not united in their fasting?

Difficulty in sighting the moon in industrialized areas

There is nothing wrong with sighting the moon by means of modern instruments

They did not see the new moon of Dhu’l-Hijjah – what should they do?

If he travels during Ramadaan to another country that started the fast at a different time, how should he fast?

If he starts fasting with a country that uses calculations, should he break the fast with them?

Every person who is resident in a country is obliged to start and end the fast with its people

A questioner is commenting on the previous answer about fasting and the hadeeth of Ibn ‘Abbaas about moon sighting with one witness

Ruling on fasting and breaking the fast of one whose testimony was rejected or who was not able to inform the authorities

The Muslims should cooperate in sighting the moon and informing the authorities