The people in his mosque pray Fajr before the proper time; should he pray with them?

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Check below answers in case you are looking for other related questions:
Delaying Fajr prayer beyond the proper time
Delaying ‘Isha’ prayer in Ramadaan

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Related Answers:
Which is the middle prayer?
Times when it is forbidden to offer voluntary prayers
Using a timetable to know the times of prayer
Delaying Fajr prayer beyond the proper time
Delaying ‘Isha’ prayer in Ramadaan

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