2 Samuel - Chapter 14
In this chapter Joab uses an elderly widow to tell a story to David which is similar to his own troubles with his son, Absalom. In this way he is trying to deliver a reconciliation between David and Absalom.
In his commentary on this chapter, David Guzic describes this as one of the best gospel texts in the Old Testament.
"He says that if we are under the chastening of God, we may feel like banished ones. Yet we can put our place of being His banished one, belonging to Him and trusting Him to bring us back to Him. God has devised a way to bring the banished back to Him, that they might not be expelled from Him. The way is through the person and work of Jesus, and how He stood in the place of guilty sinners as He hung on the cross and received the punishment that we deserved."
Absalom does not deserve to be forgiven or restored. But forgiveness from David, and forgiveness through Jesus, do not depend on our deserving it.