WARNING ABOUT THE DAY OF RESURRECTION!
VERSES NO.1-3
Here, God swears by the mansions of stars and the Promised Day which all divine prophets and messengers have promised and the bearer of witness on the Day of Resurrection including Islam Prophet (SA), other prophets, angels and man's organs, day and night and such like, and what for which witness is borne, that is men or their deeds.
He warns that there is a Day of Judgment with witnesses who have registered all deeds for reckoning. The unjust torturers are warned that their behaviors with the real believers are all registered and recorded and kept for the Promised Day!