Having helped his disciples pray, Jesus now gave them incentive to pray. He contrasted the character of God and the character of the reluctant neighbor in His story (cf. Luke 11:13; Luke 18:1-8). This parable contains a very helpful and encouraging revelation of God"s character (cf. Luke 10:22). Understanding the character of God removes many of the problems we have with prayer. [1] This parable also encourages disciples to pray in spite of no immediate answers. It addresses the common feeling that prayer may be useless since God does not grant answers as one might expect Him to. [source][source][source]
"The point of the parable is clearly not: Go on praying because God will eventually respond to importunity; rather it is: Go on praying because God responds graciously to the needs of his children." [2][source]