They say, “If you are telling the truth, when will it be fulfilled?”
Sayyed Abbas Sadr-Ameli
And they say: �When shall this promise (of chastisement) come to pass, if you are truthful?
Al-muntakhab fi tafsir al-Qur'an al-Karim
And in their challenge to the occurrence of punishment they say: " When will that promised punishment come to pass if indeed you are declaring the truth!"