وَلَا تَقۡتُلُواْ ٱلنَّفۡسَ ٱلَّتِى حَرَّمَ ٱللَّهُ إِلَّا بِٱلۡحَقِّ‌ۗ وَمَن قُتِلَ مَظۡلُومً۬ا فَقَدۡ جَعَلۡنَا لِوَلِيِّهِۦ سُلۡطَـٰنً۬ا فَلَا يُسۡرِف فِّى ٱلۡقَتۡلِ‌ۖ إِنَّهُ ۥ كَانَ مَنصُورً۬ا (١٧:٣٣)

And slay not the life which Allah hath forbidden save with right. Who so is slain wrongfully, We have given power unto his heir, but let him not commit excess in slaying. Lo! he will be helped (17:33).

Correlating Hadith

From Abu Ja’far [Imam al-Baqir] regarding His Words: “And slay not the life which Allah hath forbidden save with right. Who so is slain wrongfully, We have given power unto his heir, but let him not commit excess in slaying. Lo! he will be helped" [17:33]. He [Imam al-Baqir] said: "He is [Imam] Hussain bin Ali, being killed unjustly, and we are his awliya' (guardians). The Qa'im [Imam al-Mahdi] from us, when he rises, would seek revenge for Hussain, so he would kill to the extent that it would be said, ‘He has exceeded in the killing.'"

امام باقر (علیه السلام)-عن قوله تعالى: (وَ مَنْ قُتِلَ مَظْلُوماً فَقَدْ جَعَلْنا لِوَلِیِّهِ سُلْطاناً فَلا یُسْرِفْ فِی الْقَتْلِ إِنَّهُ کانَ مَنْصُوراً ) قَالَ هُوَ الْحُسَیْنُ‌ بْنُ‌عَلِي (قُتِلَ مَظْلُوماً وَ نَحْنُ أَوْلِیَاؤُهُ وَ الْقَائِمُ مِنَّا إِذَا قَامَ طَلَبَ بِثَأْرِ الْحُسَیْنِ فَیَقْتُلُ حَتَّی یُقَالَ قَدْ أَسْرَفَ فِی الْقَتْلِ

Sources

Kamil al-Ziyarat, ch. 18, pg. 82; Yanabi' al-Mawwada, pg. 425; Tafsir Ayyashi, vol. 2, pg. 290.

تفسیر اهل بیت علیهم السلام ج8، ص168/ بحارالأنوار، ج44، ص218/ العیاشي، ج2، ص290/ نورالثقلین/ البرهان