There is no such thing as Shab-e-Barat in Islam,
all narrations used to prove offering Nafil Salat on the night of 15th Shabaan &
visiting graveyards are fabricated or unauthentic. If details are required, the
same can be provided regarding such hadiths InshAllah, right now we are writing
authentic narrations regarding Shabaan.
Aisha (RadiAllahu Tala Anha) says: "I have seen Prophet Muhammad (SallAllah-u-Alaihi-wa-Sallam) fast in the month of Ramadaan and I have seen him (SallAllah-u-Alaihi-wa-Sallam) fast a lot in Shabaan"
[Sahih Bukhari & Sahih Muslim]
Osama (RadiAllahu Tala Anho) says: I said Oh ! Prophet of Allah (SallAllah-u-Alaihi-wa-Sallam) I have never seen you keep so many fasts in any month in the
months like in Shabaan.
Prophet of Allah (SallAllah-u-Alaihi-wa-Sallam): This
is the month in which people are unaware meaning between Rajab & Ramadaan, this
is the month in which people 's deeds are ascended towards the Lord of the
Worlds, so I want my deeds to be ascended at a time when I am fasting.
[Nasai, Behqi (Shuab-ul-Eman), Sanad: Sahih]
Abu Huraira (RadiAllahu Tala Anho) says: Prophet of Allah (SallAllah-u-Alaihi-wa-Sallam) said: when Shabaan reaches its half, don't fast after it.
[Narrated in Tirmizi, Imam Tirmizi called this hadith Hassan Sahih]
We should fast a lot in Shabaan but not after the 15th.
Imran bin Hasban (RadiAllahu Tala Anho) says: Prophet (SallAllah-u-Alaihi-wa-Sallam) said to some person "Did you fast in the center of this month?"
He said: No
Prophet of Allah (SallAllah-u-Alaihi-wa-Sallam) said: When you are free of fasting
of Ramadaan then fast for two days instead."
The 15th shabaan should be observed with a fast, if left then two should be kept
in replacement after Ramadaan.
Aisha (RadiAllahu Tala Anho) says: Prophet of Allah (SallAllah-u-Alaihi-wa-Sallam)
used to fast and we used to say he won't do iftaar (meaning wouldn't stop). Then
he would do iftaar, when left fasting he would keep leaving and we then used to
say he doesn't have any intention of fasting. He (SallAllah-u-Alaihi-wa-Sallam)
used to recite Surah Bani-Israel & Surah Az-Zumur every night (during the
month of Shabaan).
[Musand Ahmad, Buloogh ul Amani 10/200, Sanad: Jaiyed]