“When nature prompted and no law denied Promiscuous use of concubine and bride;
Then Israel’s monarch after Heaven’s own heart,
His vigorous warmth did variously impart
To wives and slaves.”

From which poem are these lines taken?

The correct option is Absalom and Achitophel: A Poem.

These lines are the opening verses of John Dryden's famous satirical poem, Absalom and Achitophel, first published in 1681.
In these opening lines, Dryden describes a past, biblical era in Israel where polygamy and concubinage were socially and legally accepted, referring specifically to the Biblical King David ("Israel’s monarch after Heaven’s own heart"). This biblical setting serves as an allegorical representation of 17th-century England under King Charles II, who was notorious for his numerous mistresses and illegitimate children, including James Scott, Duke of Monmouth (who represents Absalom in the poem).