He is living in Germany – should he fast with the European Islamic Society or with Saudi?
Question

                We are living in Germany and the problem is that the imam of one mosque says “We will fast with Saudi” but in another mosque they said, “We will fast following the European Islamic Society which supposed to have undertaken the mission to watch for the moon.” What is your opinion? May Allaah reward you with good?.
Praise be to Allah.If the 
    European Islamic Society depends on sighting the moon, then it is better for 
    you to follow them with regard to starting and ending the fast. 
There is an 
    ancient and well known difference of scholarly opinion concerning this 
    matter – should each land have its own sighting or should everyone follow 
    those who see the moon even if the sightings differ from one country to 
    another? This difference of opinion is permissible and is based on ijtihaad, 
    and there is no sin on anyone if he follows one of these two opinions, 
    according to the evidence that becomes clear to him. Perhaps the more 
    correct view is that the difference in sightings is relevant in this issue. 
    We have explained the evidence for this view in the answer to question no. 
    50487. 
Among the 
    evidence that supports that is the report narrated by Muslim (1819) from 
    Kurayb, that Umm al-Fadl bint al-Haarith sent him to Mu’aawiyah in Syria. He 
    said: I came to Syria and did her errand, then the new moon of Ramadaan came 
    when I was in Syria, and I saw the new moon on Thursday night. Then I came 
    to Madeenah at the end of the month and ‘Abd-Allaah ibn ‘Abbaas (may Allaah 
    be pleased with him) asked me about the new moon. He said: “When did you see 
    the new moon?” I said: “We saw it on Thursday night.” He said: “Did you see 
    it?” I said: “Yes, and the people saw it, and they fasted, and Mu’aawiyah 
    fasted.” He said: “But we saw it on Friday night, and we will carry on 
    fasting until we complete thirty days or we see it.” I said: “Is not the 
    sighting and fasting of Mu’aawiyah sufficient for you?” He said: “No; that 
    is what the Messenger of Allaah  (peace and blessings of Allaah be upon 
    him) enjoined upon us.” 
This 
    indicates that when lands are far apart, each land has its own sighting, and 
    it is not obligatory for everyone to fast when one land sees the moon. 
And Allaah 
    knows best.