This is the one of the most common types of irony used by Shakespeare and there are many instances of it in Macbeth.E.g.
“Fair is foul, and foul is fair” is the motto of the witches, something that Macbeth unknowingly echoes in his first line, “So fair and foul a day I have not seen”. This indicates to the audience that Macbeth and witches are already connected in spirit before they have even met.
Duncan says, referring to the Thane of Cawdor, that “There’s no art/ To find the mind’s construction in the face./ He was a gentleman on whom I built/ An absolute trust.” This is ironic because after Macbeth becomes the Thane of Cawdor, the same words may be applied to him and he becomes a “most disloyal traitor”, just as the previous Thane of Cawdor was.
When Duncan visits Inverness, he says that the castle has a “pleasant seat” and Banquo is quick to agree, saying that the “air is delicate”, neither of them knowing that Macbeth is planning to murder Duncan in this castle.
After the murder of Duncan, Macbeth says that his “hand will rather/ The multitudinous seas incarnadine” but Lady Macbeth scoffs at this and says, “A little water clears us of this deed.” The irony of this is only brought to light in Act 5, Scene 1 when Lady Macbeth, while sleepwalking, constantly washes her hands and says, “Here’s the smell of blood still; all the perfumes of