Hanafi Fiqh: Imsak and Fasting
Answered by Shaykh Faraz Rabbani
These two online resources appear to give a difference of opinion (in the Hanafi school) pertaining to when one must start fasting. http://www.sunnah.org/ibadaat/fasting/Ramadan_terms.html
1.0 THE OBLIGATION OF FASTING. 1. The time for fasting is from the rising of the SECOND dawn until the setting of the sun.
* Which is the more reliable opinion?
* When is the start time for fasting in the other schools – the false/first dawn or the true/second dawn?
There is no difference. There are two dawns. The first is false dawn (al-fajr al-kadhib), which occurs when the sun begins to get towards the horizon, such that a little vertical light is visible in the sky, but it then disappears. The second is true dawn (al-fajr al-sadiq), which is when light spreads horizontally across the horizon. [Maraqi, Radd al-Muhtar]
Note, however, that this is not normally visible in cities, because of the amount of lighting and atmospheric pollution.
And Allah knows best.