منْ زَارَهُ يُرِيدُ بِهِ وَجْهَ اللّه ِ أَخْرَجَهُ اللّه ُ مِنْ ذُنُوبِهِ كَمَوْلُودٍ وَلَدَتْهُ أُمُّهُ،
Imam Sadiq (as): the one who visits Imam Hussein's grave for the pleasure and satisfaction of God, the lord of the universe purifies him and removes all his sins as if he is just born.
source : erfan.ir