Allah's (Subhanahu wa Ta’ala) mercy is forever raining on us, but especially for the sake of the sinful worshippers, Allah (Subhanahu wa Ta’ala) has fixed some special days and nights for forgiveness of sins and pardon.
For all the Muslims who spend their lives in the shade of Islam, every year there are a few blessed nights. Each of them has separate blessings and every night has different characteristics. The Holy Quran especially mentions 3 nights:
1. Shab Meraj, in which the Lord and His worshipper met. The verse of Surah Isra:
Holy (free of any imperfection, weakness and insufficiency) is He Who took His (most beloved and intimate) Servant in a small portion of a night from the Sacred Mosque to the al-Aqsa Mosque, whose surroundings We have blessed, in order that We might show him (the Perfect Servant) Our Signs. Surely He is the One Who is All-Hearing, All-Seeing. Surah Isra (17:1)
Here "the night" mentioned is by consensus Shab Meraj.
2. Shab Qadr, which is the night of the revelation of the Holy Quran, in which angels descend and on this night, the worshippers of the Lord are given the reward of more than 1000 months of worship.
The Night of Destiny is better than a thousand months (in merit of excellence, blessings, reward and recompense). Surah Qadr (97:3)
3. Shab Baraat: This is the night in which the glad tidings of forgiveness and pardon are given to the worshippers of Allah (Subhanahu wa Ta’ala). This night is mentioned in the following verses of the Holy Quran:
Ha, Mim. (Only Allah and the Messenger [blessings and peace be upon him] know the real meaning.)
By this Light-Giving Book,
Surely We have sent it down in a blessed night. Surely We are the Warner.
In this (night) judgment is given on all matters of wisdom (separately). Surah Dukhan (44:1-4)
A group of the Mufassirin and the scholars interpret this “Lailatul Mubarakah” as the 15th night of Sha’abaan, which is called as Lailatul Baraat.