I am a sister from south India. Recently I came to know that some people in my locality are fasting and celebrating eid based on moon sighting in Saudi Arabia and not based on the local moon sighting. And they are saying that one should follow the moon sightings of Saudi Arabia as there is hadees regarding this matter(Allah is all knowing).Is that true? Please help
n the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
The commencement of the lunar month by Saudi Arabia is based on the mere birth of the moon and not the actual sighting.  This is also clear from the latest decision of the commencement of Dhul-Hijjah of this year (1439/2018). It was impossible to have sighted the crescent during the partial solar eclipse anywhere the world.    
You may also read the opinion of our honoured Mufti Ebrahim Desai Sahib in regard to moonsighting issues from the following links. 
And Allah Ta’āla Knows Best
Checked and Approved by,
Mufti Ebrahim Desai.