Narrated that Imam Sadiq (as) said,

"Recite the following when you come to the grave of al-Husain bin Ali (عليه السلام), and you may also recite the same besides the graves of all Imams (عليهم السلام)"

ثمّ تقول : اللّهُمَّ الْعَنِ اللَّذَيْنِ بَدَّلا نِعْمَتَكَ ، وَخَالَفا كِتابَكَ ، وَجَحَدا آياتِكَ ، وَاتَّهَما رَسُولَكَ ، احْشُ قُبُورَهُما وَأجْوافَهُما ناراً وَأَعَدَّ لَهُما عَذاباً أليماً ، وَاحْشُرْهُما وَأشْياعَهُما وأتْباعَهُما إلى جَهَنَّمِ زُرْقاً ، وَاحْشُرْهُما وَأشْياعَهُما وأتْباعَهُما يَومَ الْقيامَةِ عَلى وُجُوهِهِم عُمْياً وَبُكْماً وَصُمّاً ، مَأواهُمْ جَهَنَّمُ كُلَّما خَبَتْ زِدْناهُمْ سَعِيراً

"O Allah, curse the two (i.e. Abu Bakr and Umar) who changed Your blessing, opposed Your Book, rejected Your signs, and accused Your Messenger. Fill their graves and bellies with fire and prepare a painful chastisement for them.

Gather the two of them and their associates & their followers in hell with blind eyes. And on Judgment Day raise the two of them and their associates & their followers on their faces, blind and dumb and deaf; their abode is hell; whenever it becomes diminished, We will increase to their burning."

[Source: Kamil al-Ziyarat, Ch. 104, Hadith. 2]