Act 4 scene 1
Answers 1Add Yours
You are probably alluding to when the witches give Macbeth the crazy potion and then vanish. Macbeth finishes having his visions and sees Lennox. He asks Lennox if he had seen the witches and adds,
"Infected be the air whereon they ride,
And damn'd all those that trust them!"
The irony here is painfully obvious. Macbeth evidently trusts them enough to seek them out and act on their little riddles.