The chapter
Every morning since the first morning, the sun has asked permission and risen from its east. One morning it will not. The Prophet ﷺ read the cosmic mechanics into Surah Ya-Sin's line: "and the sun runs to a settled term", and told Abu Dharr its destination: it prostrates beneath the Throne and seeks leave, and leave is granted; until the morning it is told: "Return whence you came." And it will rise from its setting-place, over a world that finally, unanimously, believes, one sunrise too late.
"The Hour will not be established until the sun rises from its west; and when it rises and the people see it, all of them together will believe, and that is when belief will not benefit a soul that did not believe before, or earn good in its belief." The Qur'anic clause the hadith unpacks is 6:158: the day one of your Lord's signs arrives, the account of intention is frozen. Not because mercy tired, the same Prophet ﷺ said: "Allah extends His hand by night to accept the repentance of the day's sinner, and extends His hand by day to accept the repentance of the night's sinner, until the sun rises from its west." Fourteen centuries of an open hand, renewed twice daily; the western sunrise is simply the hand closing on schedule, announced.
The scholars call this the first of the heavenly signs, the shift from history to cosmology. Dajjal, the Descent, the hordes: terrestrial, survivable, a matter of sides. This is neither. It is staged in the one theater no propaganda can reach, timed for the hour every human on earth checks: dawn. And its twin follows the same day or close upon it, Sahih Muslim pairs them: "The first of the signs (in this kind) to emerge is the rising of the sun from its west, and the emergence of the Beast upon the people in the forenoon; whichever of the two precedes, the other is close behind it."
The fiqh of this node is one word long: now. Every deferred tawbah in history is a bet that tonight is not the night and this dawn is not the dawn. The Codex sets this tile in the sequence like a sealed envelope with a known content and an unknown date, and quotes the hadith the door swings on: "Whoever repents before the sun rises from its west, Allah will accept his repentance."