Scene 3 is mostly involved with quibbles, wordplay, and literal misunderstandings. Sir Toby and Sir Andrew cannot seem to understand the real meanings of one another, or of Maria either; the confusion begins when Sir Toby attempts to introduce Sir Andrew to Maria. Sir Andrew tends to mince his words badly, as when he addresses Maria as "fair shrew," which is quite a paradox; he intends the statement to be a kindly one, but a shrew refers to an ill-tempered woman, one who would certainly not be addressed as "fair" (). Sir Toby tells Sir Andrew to "accost" Maria, meaning to proposition her; Sir Andrew asks what "accost" means, and Toby thinks that his friend is asking who Maria is. Sir Andrew then wrongly assumes that Maria's name is Miss Mary Accost, and then Toby is forced to explain the no-so-delicate meaning of "accost" before the party: "woo her, assail her," he explains the term to mean (). Although Sir Andrew is not the most perceptive of men, he does sense that Maria thinks both of them are fools: "do you think you have fools in hand," he asks her, meaning does she think she is in the company of fools (l. 61). Maria proceeds to take the question literally: she answers, "I have not you by th' hand," confessing her poor opinion of them both (l. 62). Sir Andrew takes this in a good-natured way, giving her his hand to shake.
Fenena and the Israelite prisoners are led in to be sacrificed ( Va! La palma del martirio / "Go, win the palm of martyrdom"). Fenena serenely prepares for death. Nabucco rushes in with Abdallo and other soldiers. He declares that he will rebuild the Temple of Jerusalem and worship the God of the Israelites, ordering the destruction of the idol of Bel. At his word, the idol falls to the ground of its own accord and shatters into pieces. Nabucco tells the Israelites that they are now free and all join in praise of Jehovah. Zaccaria proclaims Nabucco the servant of God and king of kings. Abigaille enters, supported by soldiers. She has poisoned herself. She begs forgiveness of Fenena, prays for God's mercy and dies.