There are numerous examples of verbal irony in the conversation between Macbeth, Macduff and Lennox soon after their arrival at his castle, Inverness. The king had lodged there for the night and Macduff enquires after him:
Is the king stirring, worthy thane?
There are two samples of verbal irony. First in Macduff's simple question and second in Macbeth's even simpler reply. Firstly, Macduff calls Macbeth 'worthy', meaning a person who deserves respect, praise and commendation for the good that he/she has done, but Macbeth is far from 'worthy.' He is, in fact despicable and not deserved of any praise for he has just committed a foul deed. He murdered his cousin, the king, whilst he was sound asleep and therefore defenceless. Although he had his guards with him, they were in a drunken stupor and hardly responded when Macbeth committed his heinous crime. It is therefore deeply ironic that Macduff should call him 'worthy.' This is also an example of dramatic irony for the audience knows what Macbeth has done but Macduff and Lennox do not.
Macbeth's reply is ironic since he knows that it is impossible for the king to make any move. He, Macbeth, has made sure of that. He killed Duncan but replies as if there is a possibility that the king might stir, i.e. awaken, but Duncan has been untimely sent to his eternal rest.
Further irony lies in the fact that Macduff mentions that he has 'almost slipped the hour' in meeting the king, and he has actually missed meeting the king, forever. Macbeth's statement' 'I will bring you to him' is further irony, for his words imply that the king is still alive, when he is not.
Added to this is Macduff's statement about this being a 'joyful trouble' for Macbeth without realising how true his words actually are. Macbeth expresses the fact that his duty to take care of his liege, 'physics pain,' i.e. it is a soothing balm or medication to what strife or pain he may be experiencing, is entirely correct, but not in the manner that Macduff understands it.
Macbeth had been in torment about killing his king and has now been relieved that the deed has actually been done. Furthermore, he has now removed the biggest stumbling block in his aspiration to be king. With the king dead, it would be much easier for him to ascend the throne.
Additionally, he states that he did "kill them," and while the others believe he is strictly speaking about the guards, the fact is that "them" also includes King Duncan.
Macduff and Lennox arrive the next morning after the murder, and Macbeth acts as if nothing happened. He shows Macduff to Duncan's room, and discusses the night before with Lennox. Lennox is describing the rough night he had. He says he heard screams of death, and Macbeth comments, ''Twas a rough night" . This is an example of verbal irony because it seems to Lennox that Macbeth is commiserating with him, when in actuality, he is commenting on his own murderous night.