In Act IV of Macbeth, there are two passages that contain imagery related to sickness. The first passage is from Macbeth's aside, where he refers to the supernatural events surrounding him. The second passage is from Lady Macbeth's dialogue with Macbeth, where she dismisses his guilt and tries to convince him to wash away the gruesome sight of blood.
In Act IV of Macbeth, there are two passages that contain imagery related to sickness. The first passage is from Macbeth's aside: 'This supernatural soliciting, Cannot be ill, cannot be good: if ill.' Here, Macbeth is referring to the supernatural events surrounding him, which he sees as neither good nor bad, but rather as something beyond understanding.
The second passage is from Lady Macbeth's dialogue with Macbeth: 'A foolish thought, to say a sorry sight.' Lady Macbeth is dismissive of Macbeth's guilt and refers to it as a 'foolish thought.' She tries to convince him to wash away the guilt and not dwell on the gruesome sight of blood on his hands.