Matthew Poole and continuators on Exodus 20:13

13 Thou shalt not kill .

To wit, any man or woman, without authority and without just cause: which exception must necessarily be understood, because many other Scriptures command the Magistrate to kill great offenders. And this prohibition, being delivered by God who made and searcheth and commands mens hearts must be extended not onely to the external act of killing, but to all motions of the heart or tongue which tend that way, as anger, hatred, envy, malice, strife, blows, and the challenges of Duellists, which is clearly manifest by comparing this with other Scriptures, as Mat. 5. 21. 1 Ioh. 3. 15. &c. And here, as in the rest, is commanded the contrary duty of preserving the lives of our neighbours, as much as lies in our power.

Marginal references: Rom. 13. 9▪