Imam as-Sadiq (pbuh) has said "Whosever prays during the nights of Ayyamul Biydh stands at the door of the abundant favours and bounties".The recommended dua is Dua Al Mujeer.
It is a means for forgiveness of sins even if they are equal to raindrops, leaves on a tree or sand in a desert.
This Dua was revealed to theprophet (pbuh) when he was prayingat Maqam-e-Ibrahim.
Other benefits of the Dua are: