27:71

An-Naml 27:71

وَيَقُولُونَ مَتَىٰ هَٰذَا ٱلْوَعْدُ إِن كُنتُمْ صَٰدِقِينَ

Wa yaqooloona mataa haazal wa'du in kuntum saadiqeen

They also say: "Tell us when this threat will come to pass, if you are truthful."