1801, Daniel Defoe, The Life and Most Surprising Adventures of Robinson Crusoe, of:
Conversation is immoral, where the discourse is undecent, immodest, scandalous, slanderous, and abusive.
1903, Edited by Professor Arber and Thomas Seccombe, An English Garner:
Such usage is very undecent from one Gentleman to another, and does not at all contribute to the discovery of Truth, which ought to be the great End in all disputes of the Learned.