I am sure you already know that hours of the day are different in different parts of the world and during different seasons. Why did Islam not standardize the hours of fasting?
We know that fasting starts at sunrise and ends at sunset, but in some parts of the world it may take more than 20 hours. Was the prophet (pbuh) not aware of it?
Daytime – the time during which the sun shines on a particular region of the earth – symbolizes life for that part of the earth. Active life has traditionally been related to the time during which the sun keeps the particular part of the world illuminated. The remaining part of the day is basically a time of inactivity and sleep. It is for this time of active life during the day that Islam has prescribed fasting. In other words, Islam wants its adherents to fast through the daytime, symbolizing a training session that starts with one’s active life and ends at, or close to, the time of one’s retirement for the day. Fixing hours for fasting rather than relating it to the rising and setting of the sun would obviously have removed this symbolic implication from the timings prescribed for fasting, as fixing hours for fasting, would have meant severing its relation with the movement of the sun. In my opinion, it is primarily for this reason that Islam has not standardized the hours of fasting and has related the duration of fasting with the rising and the setting of the sun in the particular region, even if it meant a longer fasting time for a particular region in a particular month of Ramadhan and a shorter fasting time for another region during that month.
I hope this helps.
Moiz Amjad on behalf of UIUK