Mohammad bin Muslim narrated from JAAFAR BIN MOHAMMAD AL - SADIQ (ASWS) who said:
HUSAIN bin ALI (ASWS) is with ALLAH (SWT) now and he looks at his grave and the place where he was killed. He looks at those who go to his Ziyarat and he knows them. He knows their names and the name of their fathers, and he knows their status and rank in ALLAH (SWT)’s eyes better than you know your (own) children.
He sees those who cry on him and he seeks forgiveness for them, and he asks his father to seek forgiveness for them and he says, “If my visitors knew what reward ALLAH (SWT) has prepared for them, their happiness for themselves would be greater than their sorrow for me.”
Imam Al-Sadiq (ASWS) added:
“Those who go to the Ziyarat of HUSAIN (ASWS) return with no sins.”
(Ref: Amaali of Tousi 1:54. Bihar Al-Anwar 101:64.)