In which of Shakespeare's plays are the following lines: "The quality of mercy…

Identifying the source of a quoted line of Shakespeare rests on matching its content, speaker, and stage setting to the mood and central conflict of that particular play, since each play builds its most quoted lines around its own dominant theme (romance, ambition, courtroom justice, or magical comedy).

The lines "The quality of mercy is not strained. It droppeth as the gentle rain from heaven" are spoken by Portia, disguised as a young lawyer, during the trial scene in The Merchant of Venice (Act 4, Scene 1). She is pleading with Shylock to release Antonio from his bond for a pound of flesh, arguing that mercy cannot be forced by law — it must be freely given, like rain falling from the sky — directly tying the passage to the play's central conflict between strict legal right and voluntary compassion.

None of the other offered plays shares this courtroom-mercy scene:

• Romeo and Juliet follows the doomed romance of two feuding families' children and ends in their deaths; it never stages a legal trial or a plea for mercy toward a debtor.

• Macbeth traces a general's murder of King Duncan and his descent into guilt-driven tyranny; its dominant imagery is blood, ambition, and paranoia, not courtroom compassion.

• A Midsummer Night's Dream is a comedy of mismatched lovers and fairy mischief in an enchanted forest; it contains no legal proceeding or debate over justice versus mercy.

Since the passage's speaker, setting, and theme match only the trial scene of The Merchant of Venice, that is the play the lines belong to.