In this universe, the Prophets and the angels are innocent and the Auliya are saved by Allah (Subhanahu Wa Ta'ala) from sins. Either deliberately or unwittingly, common men end up committing sins. Allah (Subhanahu Wa Ta'ala) has not only given warnings on committing sins, He has also encouraged people to ask for His forgiveness and Allah (Subhanahu Wa Ta'ala) has called Himself as Ghaffar (The forgiver), so that people have hope that Allah (Subhanahu Wa Ta'ala) may forgive them and the height of His benevolence is that in this limited earthly life, He has granted many special days and nights in which the sinners are easily forgiven. One among these special days and nights is Shab Bara'at. It is given in the Hadith:
Translation: It has been narrated on the authority of Hadhrat Abu Moosa 'Ash'ari (May Allah SWT be well pleased with him) that the Holy Prophet (Sallallahu alaihi wa sallam) said: In Shab Bara'at, Allah (Subhanahu Wa Ta'ala) casts His radiance of mercy and forgiveness on the worshippers; and except those who associate others with Allah (Subhanahu Wa Ta'ala) (Mushrik), those who bear ill will towards others, those who hold the wrong ''Aqida, the whole creation is forgiven.
(Sunan Ibn Majah, Pg. No. 99, Hadith No: 1380; Musnad Ahmed Hadith No: 6353; Shu'abul Iman Vol. 2, Pg. No. 121, Hadith No: 3672; Al Mojam Kabeer, Vol. 2, Pg. No. 109; Hilyatul Auliya, Vol. 5, Pg. No. 191; Musannaf Ibn Abi Shaiba, Vol. 7, Pg. No. 139 Hadith No: 150; Al Matalib Ul A'aliya li ibn Hajr Asqalani, Hadith No: 1133; Mojam Ausat Tabarani, Hadith No: 6967; Mojam Kabeer Tabarani, Hadith No: 16639, Musannaf Abdur Razzaq, Vol. 4, Pg. No. 317, Hadith No: 7923, Majma Uz Zawaid, Vol. 8, Pg. No. 65, Kanz Ul Ummal, Hadith No: 35175, Subul Ul Huda War Rashad, Vol. 8, Pg. No. 433, Tafseer Durre Manthur, Vol. 5, Pg. No. 741- Surah Dukhan)
Explaining the Arabic word" Mushahin" which is mentioned in the Hadith, Imam Auza'i (May Allah SWT shower His Mercy on him) writes that this word means those who hold the wrong 'Aqida and have gone outside the 'Aqida of the Ahle Sunnah, as given in Sunan Ibn Majah, Pg. No. 99.
Hadhrat Shah Abdul Haq Muhaddith Delhwi (May Allah SWT shower His Mercy on him) writes the meaning of the abovementioned word: Those who hold the wrong 'Aqida which is outside the 'Aqida of the Ahle Sunnah. (Mushahin)
This word comes from "Shahna," which also means wrongly hating somebody and having enmity.
In Shab Bara'at, Allah (Subhanahu Wa Ta'ala) forgives everybody. They include those who commit major and/or minor sins and those who do something against the preferred way as well. The word forgiveness here has vast meaning. It means forgiveness of sins for the sinners and granting Qurb to those who are virtuous.
As per this Hadith, 2 kinds of sinners will not be forgiven even on this night. One is a Mushrik, i.e. those who associate somebody with Allah (Subhanahu Wa Ta'ala). This is such a major sin that Allah (Subhanahu Wa Ta'ala) has called it a great wrong:
Behold, Luqman said to his son admonishing him: "O my son! Join not in worship (others) with Allah: for false worship is indeed the highest wrong-doing."
Surah Luqman (31:13)
This (coming) verse also mentions that the Mushrik will never be forgiven.
Allah forgiveth not that partners should be set up with him; but He forgiveth anything, else to whom He pleaseth; to set up partners with Allah is to devise a sin most heinous indeed. Surah Nisa (4:48)
Only those people will experience the sweet taste of Iman and only those people will be granted the perfection of Iman and only those people will be successful in the afterlife whose love and hate is for the sake of Allah (Subhanahu Wa Ta'ala) and the Holy Prophet (Sallallahu alaihi wa sallam)as given in the Hadith:
The one who loves for the sake of Allah (Subhanahu Wa Ta'ala) and hates for the sake of Allah (Subhanahu Wa Ta'ala); who gives for the pleasure of Allah (Subhanahu Wa Ta'ala) and withholds for Allah (Subhanahu Wa Ta'ala) achieves the perfection of Iman. (Sunan Abu Dawood, Hadith No: 4061)
Those who harbor jealousy and enmity for the love of this world, for the love of position and power, for their own sake and out of whisperings of Satan will not be forgiven on this night.
As mentioned in other Hadith, backbiters, those who are disobedient to their parents, those who let their lower garments fall below the ankle will also not be forgiven. In this Hadith, only 2 have been mentioned as these are the sources of all sins. Those who commit these 2 sins normally are not safe from the other sins as well.