Sayyiduna Abu Bakr al-Siddiq (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "When the night of the middle of Sha'ban comes (that is, Shab-e-Barat), Allah Almighty descends to the lowest heaven and forgives His servants, except that He does not forgive the polytheist and the one who holds enmity (or resentment) towards his brother."
Al-Bazzar recorded it; its chain contains Abd al-Malik bin Abd al-Malik, whom Ibn Abi Hatim mentioned in al-Jarh wa al-Ta'dil without declaring him weak. The rest of its narrators are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الأدب / 12957