They ask you: “When will this promise (of Resurrection) be fulfilled, if what you say is true?”1
Footnotes
[1]Qira’at: Ibn Kathir, Abu ʻAmr, Shuʻba, Abu Jaʻfar and Yaʻqub read it as: “. . . shall be entered into the Garden . . .”
[2]
That is, “When will the time come about which you say: Our Lord will gather you together, then He will judge between us rightly? We have been denying you persistently and opposing you openly for so long. Why is not then the judgment being passed against us?