In a lengthy tradition, the great companion Hisham Ibn Saalim (r.a.) narrates that a person came in the presence of Imam Ja’far Sadiq (a.s.) and inquired,
“O son of Allah’s Messenger (s.a.w.a.)! Should we perform the Ziyaarat of your (noble) father (viz. Imam Husain (a.s.))?”
Imam (a.s.) replied, “Yes. Recite prayers over there but do not pray in front of his grave. Rather, pray behind (i.e. facing) his grave”
He then asked, “What is the reward for the one who performs his Ziyaarat?”
Imam (a.s.) replied, “Paradise, provided he believes in his Imamate and follows him.”
He continued, “What about the one who intentionally omits his Ziyaarat?”
Imam (a.s.) responded, “He will regret it on the Day of Judgement.”
He further asked, “What about the one who spends a few days near his grave?”
Imam (a.s.) answered, “For every day he will be rewarded with 1000 months of worship.”
[Kaamil al-Ziyaaraat, chapter 44, p. 123, H. 2]
This is a very lengthy tradition. But in this initial part, Imam (a.s.) has clarified that the reward for performing Ziyaarat of Imam Husain (a.s.) will only be for the one who believes in his rightful Imamate and worships along with this belief. Believing in Imam Husain (a.s.) to be the rightful Imam necessitates the rejection of Yazid and rejecting the entire system of Caliphate which Yazid was representing. Hence, whoever visits Karbala without believing in the Imamate of Imam Husain (a.s.), it is quite possible that he might still get his worldly wishes fulfilled because Husain Ibn Ali (a.s.) is the son of the master of the universe, Imam Ali Ibn Abi Talib (a.s.). However, in the hereafter, this person will remain deprived of the great rewards of performing this Ziyaarat.
O Allah, by the right of the martyrdom of Imam Husain (a.s.), grant us the good fortune to remain steadfast upon the Imamate of the 12 Imams whom You have appointed, especially the Imam of our time, His Eminence Imam Mahdi (a.t.f.s.). Aameen, O Lord of the worlds!