Chapter 45: The Book of Oaths (qasamah), Retaliation and Blood Money
It was narrated from Al-Qasim bin Al-Mukhaimirah, from a man among the Companions of the Prophet, that the Prophet said: "Whoever kills a man from among Ahl Adh-Dhimmah.[2] he will not smell the fragrance of Paradise, and its fragrance may be detected from a distance of seventy years."
Sunan an-Nasa'i 4749