There are different interpretations about this verse. However, the most correct of them is what Jaber Ibn Abdullah has narrated that it is the first ten nights of Dhul-Hijjah (the month in which Hajj takes place).
But what is the importance of these nights so that Allah (swt) has sworn by them?
It is said that because a Muslim completes his Lord’s assignments when performing the Hajj pilgrimage which is the fifth and last pillar of Islam. In these days Muslims crowded and gathered from everywhere to perform Hajj.