Allah, the Blessed and Exalted, says: "And We prescribed for them therein (in the Torah) that a life is for a life." [Surah al-Ma'idah: 45]
And the Prophet (peace and blessings be upon him) said: "The blood of the Muslims is equal (in retaliation), one to another."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / Q15903