No, but I [: God] swear by the Doomsday!
And no, but I [: God] swear by the 'censuring soul' [: the Comforter!]
(In the name of God, Most Gracious, Most Merciful)
Such kind of oath in the Quran indicates the future; it is an oath of threatening with Doomsday, i.e. you will then be taken to account and be punished:
So that disbelievers will be punished, and believers will be taken to accounting.
It means: I swear by the 'censuring soul' who blames people about their bad deeds, and rebukes them concerning their acts;
so he will kill the disbelievers, and confirm the believers and help the religion and invite people to believe in the Lord of ‘nations and worlds’,
who will have the arguments and proofs and will interpret the Quran,
and who will be sent and raised in the end of time,
and who will be helped by the Most Gracious;
he is the author of the book (The Interpretation of the Revelation.)
is the Comforter
who will be raised in the Last Days]
It is written in the Gospel of John, chapter 16: 7-8
that the Christ foretold about the coming or advent of the 'censuring (or reproving) soul' [or the Counselor or the Comforter who will reprove the world]; he said:
“But I tell you the truth: It is for your good that I am going away. Unless I go away, the Paraclete (or the Comforter) will not come to you; but if I go, I will send him to you.
When he comes, he will reprove the world of guilt in regard to sin and righteousness and judgment.
>> So the word ‘reprove’ means: he will blame and rebuke the sinners and guilty.
>> While his saying: “in regard to righteousness” means: the food which man offers for the sake of idols, and for the sake of imams and sheikhs [and saints]: this is not allowed; but it should exclusively be offered for the sake of God alone.
Therefore, from these ayat, it is clear that God threatens the unbelievers by the Doomsday, and He threatens the blasphemers and idolaters by the Mahdi (the Comforter or Elijah):
It implies: I will send you the Mahdi (or the Comforter or Elijah) to punish and annihilate the blasphemers and idolaters.
And I will bring about the Doomsday.