What is the ruling on a group of Arab students in India fasting based on the Saudi sighting [of the moon], after India has already predetermined Ramadan without seeking to sight the crescent, while some other students are fasting according to India's timing?

"Seeing with the eye is what is considered legally valid for establishing months, based on the Almighty's saying: (So whoever among you witnesses the month, let him fast it), and the Prophet's (peace be upon him) saying: 'Fast when you see it and break your fast when you see it.' This is unlike astronomical calculations, which are not possible for everyone. Therefore, what India does is not legally valid, and sighting (the moon) must be adopted, or the sighting of the nearest Muslim country."