Sunan an-Nasa'i 4735
سنن النسائي#4735SahihIt was narrated from 'Ali, may Allah be please with him that the Prophet said:"The lives of the believers are equal in value, and they are one against others, and they hasten to support the asylum granted by the least of them. But no believer may be killed in return for a disbeliever, nor one with a covenant while his covenant is in effect
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniHasan
Zubair Ali ZaiSahih
In-book reference: 45:30