In "Othello", Iago warns, "O! Beware, my lord, of jealousy", it is this creature
[DOC] [TLE] Dr. J's Othello Study Guide [PAR] Act One scene two (I.ii): Iago warns Othello of Brabantio's anger; Cassio arrives 
to tell Othello that a war council has been ... O, beware, my lord, of jealousy!