There are a number of quotations in Shakespeare's Macbeth that refer to betrayal.
In Act Two, Macduff arrives to collect Duncan as the King had previously ordered. Macduff is the one that discovers the murder and he suspects that Duncan's murder is an act of betrayal ("treason").
Ring the alarum bell. Murder and treason!
Banquo and Donalbain! Malcolm, awake! (II.iii.79-80)
Macduff flees to England to persuade Malcolm to return to Scotland to save their homeland from the tyrant, Macbeth. However, Malcolm is not sure that Macduff isn't working for Macbeth, and he fears Macduff's betrayal.
This tyrant, whose sole name blisters our tongues,
Was once thought honest. You have loved him well;
He hath not touch'd you yet. I am young, but something
You may deserve of him through me, and wisdom
To offer up a weak, poor, innocent lamb
To appease an angry god. (IV.iii.14-19)
Malcolm suggests that Macduff may simply want to deliver Duncan's heir and the next in line to the Scottish throne to Macbeth, so...
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