Praise be to Allah, and may peace and blessings be upon the Messenger of Allah.
It is established from the Prophet ﷺ that the Hour will begin on a Friday. He ﷺ said:
“The best day on which the sun has risen is Friday. On it Adam was created, on it he was admitted into Paradise, on it he was expelled from it, on it his repentance was accepted, on it he died, and on it the Hour will be established.”
This is an authentic text establishing that the Hour will begin on Friday.
As for the issue concerning the differences in time zones between countries, the answer is that the Day of Judgment and its events will not be like the days of this worldly life and their circumstances. The Hour will begin when the entire system of the world undergoes a transformation, and the system of the sun, moon, stars, celestial bodies, night, and day will also change.
Therefore, it is not correct to compare that day with the timekeeping system we know today. The current system of timekeeping is based on the succession of night and day, the movement of the sun, and differences in the times of sunrise and sunset. All of this belongs to the system that will change when the Hour begins.
The Prophet ﷺ also informed us of a tremendous change that will occur to the sun near the end of time, including its rising from the west. In an authentic hadith, he ﷺ stated that the sun travels until it reaches its place of setting beneath the Throne. Then, one day, it will be told: “Return from where you came.” It will then rise from the west, and this will occur when faith will no longer benefit a soul that had not believed beforehand.
When the movement of the sun and its rising and setting change, it is therefore not appropriate to measure the day on which the Hour begins according to the clocks and time zones established by people in this worldly life.
The beginning of the Hour is also a tremendous event during which the system of the world as we know it will be disrupted. Allah تعالى says:
“When the sun is wrapped up.”
And He سبحانه says:
“When the sky is split apart.”
And He says:
“When the earth is shaken with its final earthquake.”
Thus, we are not required to know how the concept of “Friday” corresponds to modern time zones and the calendar established by human beings. These are details for which the revelation has not explained the manner in which they will occur. One should not go to extremes in investigating matters that Allah تعالى has not informed us about.
What is required is to believe what the Prophet ﷺ informed us: that the Hour will begin on Friday, while accepting that the manner and details of this are matters of the unseen whose knowledge Allah تعالى has kept to Himself.
What matters is not knowing the exact time when the Hour will begin, but preparing for it through repentance and righteous deeds, for the time of its occurrence is known only to Allah تعالى.
The Prophet ﷺ informed us that among the greatest signs preceding the Hour is the rising of the sun from the west. When this great sign occurs, the door of repentance will be closed. Allah تعالى says:
“On the Day when some of the signs of your Lord come, no soul will benefit from its faith if it had not believed before or earned through its faith some good.” [Al-An'am: 158]
Therefore, a person should hasten to sincere repentance, make up for what he has missed, and increase his righteous deeds before a day comes when repentance will no longer be of benefit and what has been missed can no longer be recovered.
In conclusion: The fact that the Hour will begin on Friday is established by authentic textual evidence. There is no contradiction between this and the differences in time zones between countries, because the system of time that we know is connected to the movement of the sun, night, and day. These things will change when the Hour begins, so the circumstances of that day cannot be measured according to the ordinary worldly system of timekeeping.
And Allah تعالى knows best.