إِذَا زُلْزِلَتِ الْأَرْضُ زِلْزَالَهَا ... يَوْمَئِذٍ تُحَدِّثُ أَخْبَارَهَا
When the earth is shaken ... on that day it will report its news. (99:1, 4)
Idhā marks a future time with conditional force. Classical grammatical analyses differ over what governs or answers this opening: tuḥaddithu or the later yaṣduru may be linked to it; another analysis supplies an implied command such as udhkur ('remember').
These alternatives do not remove the scene’s rhetorical unity. They differ in the syntactic connection between the initial temporal expression and the later assertions. An advanced analysis must mark the alternatives rather than assert one as the sole possible parsing.