If you were not sure, your fasting was valid.

Last year we followed a prayer calendar and fasted accordingto it. For some reason we then followed another calendar where suhoor was later because we were not sure if fajr was in correct time. Then we again returned to the old calendar cause it was safer. Do we have to make up those fasted days because we ate suhoor later and maybe fajr had already began?

Fasting |