What is the time for abstaining from food and drink during Suhoor, and is it determined by the distinguishing of the white thread from the black, or by relying on the Adhan, whose timing varies between countries? And what should one do if the Adhan overtakes them while they are eating due to forgetfulness or oversight?

One must abstain from things that invalidate the fast upon verifying the true dawn, either by direct observation or by emulating a trustworthy muezzin who is knowledgeable of the prayer times. If the muezzin does not call the adhan until the true dawn appears, then one must abstain from food and drink upon hearing his adhan, and the fasting person should spit out whatever is in their mouth. However, if the muezzin calls the adhan before the dawn, then it is not obligatory to abstain upon hearing his adhan, and one is permitted to eat until the true dawn is certain.