Classical legal terminology distinguishes false dawn (fajr awwal) from true dawn (fajr thānī). False dawn does not commence the fast; true dawn, spreading across the horizon, does.
The start of the Fajr prayer time and the start of fasting coincide as a legal boundary. Clock times vary by place and date; the source describes the sign rather than a fixed hour.
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Kitab al-Sawm: Fasting Hours, Invalidators, Qada and Kaffarah
Classical legal terminology distinguishes false dawn (fajr awwal) from true dawn (fajr thānī). False dawn does not commence the fast; true dawn, spreading across the horizon, does.
The start of the Fajr prayer time and the start of fasting coincide as a legal boundary. Clock times vary by place and date; the source describes the sign rather than a fixed hour.