Matthew 11:16-19 is the parallel account of this same comparison of 'this generation' to children in the marketplace.

Deuteronomy 32:20 calls Israel a 'perverse generation' with no faithfulness, echoing Jesus' complaint about this generation.

Lamentations 2:13 uses the same rhetorical 'to what compare' question about Jerusalem's suffering, paralleling Jesus' lament for this generation.