وَلاَ تَقْتُلُواْ النَّفْسَ الَّتِي حَرَّمَ اللّهُ إِلاَّ بِالحَقِّ وَمَن قُتِلَ مَظْلُومًا فَقَدْ جَعَلْنَا لِوَلِيِّهِ سُلْطَانًا
فَلاَ يُسْرِف فِّي الْقَتْلِ إِنَّهُ كَانَ مَنْصُورًا
“And whosoever is killed unjustly, then We have indeed given his heir an authority, but let him not exceed the limits in killing, verily he is helped”
Regarding the above verse, Imam Sadiq (as) said, This is about the Qaem of the family of the Prophet (as). When he rises, he will kill (many people), avenging the blood of Husain (as). Even if he kills everyone on earth, he will not “exceed the limits of killing.”
“But let him not exceed the limits in killing” means that he will not act unconscionably. I swear to Allah that he will kill the descendants of the killers of Husain (as) for the deeds of their fathers. (Kamiluz Ziyarat)
A person said to Imam Reza (as), O son of the Messenger of Allah! What do you say about a Hadith that is narrated from (Imam) Sadiq (as), who said, ‘When our Qaem (as) rises, he will kill the descendants of the killers of Husain (as) for the deeds of their fathers.
Imam Reza (as) replied, It is true.
I asked, Then what about the words of Allah in this verse, “No bearer of burden, shall bear another’s burden”?
Imam Reza (as) replied, Allah says the truth in all of His words. The descendants of the killers of Husain (as) are pleased with the deeds of their fathers and they boast about (these deeds). And those who are pleased with an act are just like those who commit it.
Even if a man kills someone in the east and another man in the west is pleased with that killing, he will be considered a partner in that killing in the eyes of Allah. The Qaem (as) will kill them for being pleased with the acts of their fathers.
I asked, What is the first thing the Qaem (as) will do after he rises?
Imam (as) replied, He will start with the Bani Shaybah (name of the tribe that holds the keys to the Kaabah). He will cut their hands off because they are the looters of the House of Allah. (Oyoone’ Akhbare’ Reza)
Regarding the verse – “And whosoever is killed unjustly, then We have indeed given his heir an authority, but let him not exceed the limits in killing, verily he is helped” – Imam Baqir (as) said, The one who is “killed unjustly” is Husain bin Ali (as) and we are his “heirs.”
When the Qaem (as) rises, he will avenge Husain’s (killing). He will kill so many people that some will say, “He is [exceeding] the limits.” Therefore, the verse refers to Husain (as) and the “heir” is the Qaem (as). “[Exceeding]the limits of killing” means killing those who were not involved in the killing of Husain (as).
“Verily he is helped” means that verily the days of this life will not end before a man from the family of the Prophet (as) is “helped.” He will fill the earth with justice and equity, just as it will be filled with oppression and inequity. (Tafseer Ayyashi volume 2 page 289)