Final answer:
The quote is from Shakespeare's "Romeo and Juliet," spoken by Friar Laurence to Juliet as he gives her a potion to feign death.
Step-by-step explanation:
The quote "Take thou this vial, being then in bed, / And this distilled liquor drink thou off; / When presently through all thy veins shall run / A cold and drowsy humour" is spoken by Friar Laurence to Juliet in William Shakespeare's play "Romeo and Juliet." In this scene, the Friar is giving Juliet a potion that will simulate death so that she can avoid marrying Paris and eventually reunite with her beloved Romeo.