Bible Verses About mercy killing

Thou shalt not kill.

I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service.

Now we exhort you, brethren, warn them that are unruly, comfort the feebleminded, support the weak, be patient toward all men.

And to them it was given that they should not kill them, but that they should be tormented five months: and their torment was as the torment of a scorpion, when he striketh a man.