Bukhari : Book 3 : Volume 31 : Hadith 190
Narrated 'Aisha: Allah's Apostle used to fast till one would say that he would never stop fasting, and he would abandon fasting till one would say that he would never fast. I never saw Allah's Apostle fasting for a whole month except the month of Ramadan, and did not see him fasting in any month more than in the month of Sha'ban.
Hence, the blessings of this month cannot be overlooked. But there have been introduced many bidaats (acts that have no place in quran and sunnah) in our religion in order to earn reward but these unjustified acts cannot invite any glad tidings or blessings from ALLAH swt, instead they are just prohibited acts, since MUHMMAD s.a.w.w said: “action which is not ordered by me is rejected in sight of ALLAH ” (Muslim: 1718). One such biddat is the invention of “shab-e baraat” on 15th of shaban. This night is no where seen celebrated by MUHAMMAD s.a.w.w as a blessed night but there are many people who support the truthfulness of this night by quoting the fabricated ahadith, through which they do not only visit graves but also worship the whole night by making it the night of “closing of the deeds register” and fasting.
The famous weak hadith quoted by these people is given below, which is mentioned in ibn-e majah’s hadith collection and it’s proven as a weak hadith.
{Hadrat `Ali (RA ) reported that RasulAllah (SAWS) said: "When it is the fifteenth night of Sha'baan, observe prayer during the night and observe fast during the day; for Allâh (SWT) descends to the heaven of the world as the sun sets and says: Is there anyone to seek forgiveness so that I should forgive him? Is there anyone to seek sustenance so that I should provide him? Is there anyone in trouble so that I may relieve him? And so on and so forth, until the dawn breaks." [Ibn Mâjah]}
But there is no single sahih hadith ever quoted in any sahih collection regarding 15th of shaban. The supporters of shab-e baraat quote a verse from hoyl quran regarding this night, which is the 4th verse of surah dukhan but that verse does not talk about the 15 shaban nowhere, instead, ibn-e kathir has mentioned in his tafsir of the forth verse of surah dukhan, surah qadar.
The 4th verse of surah dukhan talks about the same night i.e. the night of qadar, the night in which ALLAH swt started revealing Quran.
Let us see the first 3 verses of surah dukhan to decide what the two verse of surah dukhan talk about.
Surah dukhan: verse 2-4
“(I swear) By this manifest Book. Surely, We have revealed (this Quran) on a blessed night; so We are ever Warner with surety. Therein (this night) every affair is decided with full wisdom.”
So by seeing the verse number 4 of in context of verse number 2 and 3, it is clear that there is no such thing like shab-e baraat and the evidences and logics presented by the pro-shab-e barat people are wrong and have no place in Islam.