Final answer:
The given quote is spoken by Macbeth in Act 5, Scene 3 of Shakespeare's play 'Macbeth'.
Step-by-step explanation:
The quote "Seyton! I am sick at heart, ...Is fall'n into the sere, the yellow leaf, ...As honor, love, obedience, troops of friends, ... Which the poor heart would fain deny and dare not. Seyton!" is spoken by Macbeth in Act 5, Scene 3 of Shakespeare's play 'Macbeth'. Throughout the play, Macbeth is a character who is profoundly affected by ambition and guilt, leading to a range of actions and reflections on power, mortality, and loss. This particular speech in Act 5 reveals Macbeth's weariness and recognition of the empty rewards of his treacherous rise to power.