(Seeing that they reject your call) withdraw from them. The Day will come when the caller will call (all the people) to something exceptionally terrible
Therefore, (O Messenger) Ignore them for a while. The Day is coming when the caller will call them to a thing they have not conceived. (Shackles of captivity following the battle when they come to attack the believers.
So, turn away from them! At that time when the Caller calls to the terrifying event...
Al-muntakhab fi tafsir al-Qur'an al-Karim
Pay no attention to them O Muhammad; there shall come the day of the horrendous Event when the announcer among the angels intimates to them the painful and disturbing news of the unwelcome occurrence of the imminent judicious hearing and judgment