Why is it unsound to detach “illā mā shāʾa Allāh” from the preceding promise?

Supplementary Practice 28 — Comparative Rhetoric of Sūrat al-Aʿlā and Sūrat al-Ghāshiyah

• The exception necessarily cancels the entire promise
• The exception qualifies the promise and must be read with it
• It turns the promise into an unrelated conditional clause
• Detachment obscures what the exception qualifies