What does the Bible say about God's justice in avenging His elect?

In Luke 18:1-8, Jesus speaks of a parable where an unjust judge eventually grants a widow justice due to her persistent cries. He contrasts this with God, stating that if an unjust judge will act on behalf of a persistent seeker, how much more will a just God respond to His elect who cry out to Him continually? This assures believers that despite delays, God is ever attentive and will deliver justice speedily. The parable emphasizes the importance of persisting in prayer and trusting in God's righteousness.