On interpreting Lailatul Mubarakah as Shab Baraat, a question might be raised that it is clearly given in the Holy Quran that it was revealed in Shab Qadr, then what revelation of the Holy Quran mean in Shab Baraat?
Hadhrat Shah Abdul Aziz Muhaddith Dehlwi (May Allah shower His Mercy on him) writes about this in Tafseer Azeezi, 30th para Surah Qadr, Pg No: 259:
Translation: Here a question is raised. That is the Holy Quran was revealed completely over a period of 23 years, this began in the month of Rabe’e ul Awwal. Then, the 40th year of the blessed life of the Holy Prophet (Sallallahu alaihi wa sallam) was just starting. Whereas in the Holy Quran, 3 separate occasions are indicated. One among them is the month of Ramadhan, second Shab Qadr, which comes in the last 10 days of Ramadhan and third, Lailatul Mubrakah, which according to most Ulema is the 15th night of Sha’abaan, which is also called as Shab Baraat. Then how do you reconcile all these 2 opinions with what has happened?
The answer to this is that after a thorough research in the Hadith, what we get to know is that the revelation of Holy Quran from “Lauh Mahfooz” to “Bait Ul Izzat,” which is a high station in the heavens was done in Shab Qadr. The same year, the decision to do so was made in Shab Baraat. Now all the 3 are correct. The actual revelation was in the month of Ramadhan in Shab Qadr. The decision to do so was made in Shab Baraat and the revelation of it on the blessed tongue of the Holy Prophet (Sallallahu alaihi wa sallam) was started in Rabe’e ul Awwal and it was completed before the passing away of the Holy Prophet (Sallallahu alaihi wa sallam). After this interpretation, there is no contradiction.