What is a sound rhetorical effect of repeating al-arḍ in 99:1–2?

Supplementary Practice 25 — Comparative Rhetoric of Sūrat az-Zalzalah and Sūrat al-ʿĀdiyāt

• Necessarily cancelling the first statement
• Turning both verbs into one morphological form
• Separating two successive developments concerning the same subject
• Necessarily making the second verse a proverbial epilogue