In Act III, scene I ofMacbeth, Macbeth hires murderers to kill Banquo and Fleance. While speaking to them, Macbeth's usual iambic pentameter switches to prose. Shakespeare's decision to alternate from his typical use of iambic pentameter is no coincidence, but rather a calculated stylistic choice on his part.
Many times in Shakespeare's plays, the lower or more common characters will speak in prose or free verse, like the Porter in Act II. Macbeth's switch to prose indicates that he has lowered himself in terms of both nobility of station and morality in hiring the murderers. Macbeth's uncharacteristic use of prose is also suggestive that Macbeth is acting out of character. Speaking with the devious murderers is unsettling for Macbeth, and his dialogue and use of prose reveals his unease and distrust of the situations.