«كَلَّا سَوْفَ تَعْلَمُونَ ثُمَّ كَلَّا سَوْفَ تَعْلَمُونَ»
No indeed! You will soon know; then no indeed, you will soon know.
These are Qurʾān 102:3–4. Repeating the warning increases its force; the second statement is not merely copied information. Thumma (ثم) contributes to the heightened impact of the reiterated warning.
Repetition becomes meaningful expansion when it serves warning, emphasis or staged insistence. Mere purposeless duplication does not automatically qualify as eloquent iṭnāb.