Surah Saba 34:29

وَيَقُولُونَ مَتَىٰ هَـٰذَا ٱلْوَعْدُ إِن كُنتُمْ صَـٰدِقِينَ

And they say, "When is this promise, if you should be truthful?"

Translation: Saheeh International

Tafsir

And they say ‘When shall this promise of chastisement be fulfilled if you are being truthful?’ concerning it.

Excerpt from Tafsir al-Jalalayn, commentary on 34:29, via Quran.com. The reader has the full commentary and 9 more tafsirs.