Imam al-Rida (AS) narrated, 'The Commander of the Faithful (AS) did not used to sleep at all on three nights: the 23rd night of the month of Ramazan, the eve of Aid al-fitr, and the eve of the 15th of Shaaban. And these are the nights when sustenance is allotted, and prescribed times of death and all that is to happen in that year is decreed.