Hadith 31-179

وَبِهذَا الإسناد قالَ: قالَ رَسُولَ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَآلِهِ: إِنَّ مُوسَى بْنِ عِمْرانَ سَأَلَ رَبَّهُ عَزَّ وَجَلَّ فَقالَ: يا رَبِّ إِنَّ أَخِي هارُون ماتَ فَاغفِر لَهُ فَأَوحَى اللَّه تَعالى‏ إِلَيْهِ يا مُوسَى لَو سَألتَني فِى الأَوَّلِينَ وَالآخَرينَ لاجَبتُكَ ما خَلا قاتَلَ الحُسَيْنِ بْنِ عَلِىِّ بْنِ أَبِي طالِب‏ عَلَيْهِ السَّلامُ فَإِنِّي أَنْتَقِمُ لَهُ مِن قاتِلِه.

According to the same documentation, God’s Prophet (S) said, “Moses - the son of Imran (a.s.) asked his Lord - the Honorable the Exalted: O Lord! My brother Aaron has died. Please forgive him.” The Sublime God revealed to him, “O Moses! If you ask Me to forgive any of those of the old or those of later times I would forgive them except for the murderers of Al-Husayn ibn Ali ibn Abi Talib (a.s.). I will take revenge on his murderers.”