How do we know that persistent prayer is effective?

In the Bible, examples of persistent prayer abound, illustrating its significance. David's repeated cries in Psalm 141 show the urgency of his need and his unwavering reliance on God. Jesus Himself teaches about the power of persistence in the parable of the widow and the unjust judge in Luke 18, demonstrating that God, unlike the unjust judge, is attentive to the cries of His chosen people. Persistence in prayer reflects a deep-seated faith that God will respond, which ultimately glorifies Him. When we approach God with importunity, we express our belief in His capacity and desire to aid His people.