The prophet Muhammad was influenced by the religions of his day; in particular, during his years in Medinah, he would have been in contact with local Jews and witnessed many of their practices. It is highly likely, therefore, that the Muslim ‘night of forgiveness’ (Lailat-ul-Bara’h) was inspired by the Jewish observance of Rosh Hashanah and the days of awe leading up to Yom Kippur.
On the fourteenth of Sha’ban, the eighth month of the Islamic calendar, Muslims seek forgiveness. Many feel that it is on this night that each person’s destiny is fixed for the coming year. Some fast during the day, spending the night in prayer seeking guidance from Allah. Believers also consider this time as particularly appropriate for increasing their charitable donations.
For more see The quality of mercy or view the entire article on Restoring the balance: justice, mercy and the pearl of self-forgiveness.