""Stuff o' th' conscience" or no"

Edwin Booth as Iago in Shakespeare's Othello
Public DomainEdwin Booth as Iago in Shakespeare's Othello - Credit: J. Gurney & Son
In Shakespeare’s The Tragedy of Othello, Moor of Venice, Act 1, Scene 2, Iago says:

“Though in the trade of war I have slain men,

Yet do I hold it very stuff o' the conscience

To do no contrived murder: I lack iniquity

Sometimes to do me service: nine or ten times

I had thought to have yerk'd him here under the ribs.”