Does repentance supersede what preceded it, or will the intentional killer still face the threat of punishment in the Hereafter, even if he repents in this world?

Killing a Muslim intentionally and unjustly is one of the gravest sins. Its recompense is Hell, God's wrath, and His curse. Indeed, the perishing of the world is less significant to God than the unjust killing of a believer. However, if the killer repents with sincere repentance and performs righteous deeds, God will accept his repentance and forgive his sin. Part of his repentance is enabling the guardians of the blood to exact their right, whether through retribution (Qisas) or forgiveness, for God does not abandon the rights of His servants, and these are among the registers from which God leaves nothing.