What is the punishment for intentional killing?

The verses and hadiths indicate the enormous gravity of taking a life unjustly, and that this great sin is coupled with polytheism (shirk). Some Companions (may Allah be pleased with them) were of the opinion that there is no repentance for the premeditated murderer. However, the correct view is that repentance is possible for him, based on the generality of Allah's statement: "Indeed, Allah does not forgive association with Him, but He forgives what is less than that for whom He wills." (Quran 4:48) The rights of human beings are not waived by repentance. Therefore, the guardians of the deceased have the right to demand their right through retribution (qisas), forgiveness, or blood money (diyah).