Final answer:
Malcolm lies about having a ruthless and tyrannical nature to test Macduff's loyalty to Scotland in Act 4, Scene 3 of Shakespeare's Macbeth.
Step-by-step explanation:
The lies that Malcolm tells Macduff to test his loyalty and intentions towards Scotland can be found in Act 4, Scene 3 of Shakespeare's Macbeth. Malcolm lies about having a ruthless and tyrannical nature to test Macduff's loyalty to Scotland in Act 4, Scene 3 of Shakespeare's Macbeth.
Malcolm fabricates a series of increasingly severe vices he possesses to gauge Macduff's reaction and to see whether Macduff desires the wellbeing of Scotland or has his own self-interest at heart.
He claims to be lascivious, avaricious, and to possess numerous other vices that would harm Scotland more than Macbeth's rule, thus lying about having a ruthless and tyrannical nature.
These are calculated falsehoods intending to provoke Macduff into either agreeing with him (proving himself disloyal to Scotland), or to refute him (proving his loyalty to Scotland).