Contradiction with Matthew 9:27
This verse describes how two blind men followed Jesus and cried out for mercy, and they were not rebuked for doing so.
Matthew 9:27: And when Jesus departed thence, two blind men followed him, crying, and saying, [Thou] Son of David, have mercy on us.
Contradiction with Matthew 15:22-23
Although initially ignored, the Canaanite woman's persistence in crying out to Jesus leads to her request being granted, which contrasts the rebuke in Luke 18:39.
Matthew 15:22-23: And, behold, a woman of Canaan came out of the same coasts, and cried unto him, saying, Have mercy on me, O Lord, [thou] Son of David; my daughter is grievously vexed with a devil.
Contradiction with Mark 10:48-49
Although initially rebuked, Bartimaeus persists in crying out and Jesus stops to address him, indicating persistence is fruitful.
Mark 10:48-49: And many charged him that he should hold his peace: but he cried the more a great deal, [Thou] Son of David, have mercy on me.
Contradiction with Luke 18:1
The parable of the persistent widow encourages continual prayer and asking without rebuke, which contrasts with the crowd's rebuke in Luke 18:39.
Luke 18:1: And he spake a parable unto them [to this end], that men ought always to pray, and not to faint;