Where is there a rhyme in To Kill a Mockingbird?

In Harper Lee's "To Kill a Mockingbird," there is a rhyme mentioned by Atticus Finch when he tells his children, Scout and Jem, that it is a sin "to kill a mockingbird." He explains that mockingbirds do nothing but sing and bring joy to people, so it would be a senseless act of cruelty to harm them. This metaphorical rhyme serves as a central theme in the novel, symbolizing innocence and the unjust persecution of the pure and harmless.