Sunan an-Nasa'i 4749
سنن النسائي#4749SahihIt 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
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiIsnaad Sahih
In-book reference: 45:44