Interpretation
This parable appears in the Gospel of Luke immediately after Jesus teaches the Lord's Prayer, and can therefore be viewed as a continuation of Jesus teaching his disciples how to pray, while the verses which follow help to explain the meaning of the parable:
"I tell you, keep asking, and it will be given you. Keep seeking, and you will find. Keep knocking, and it will be opened to you. For everyone who asks receives. He who seeks finds. To him who knocks it will be opened."
— Luke 11:9-10, World English Bible
Joel B. Green suggests that the question that opens the parable ("Which of you who has a friend...?" also expressible as "Can you imagine...?") is intended to be answered as an emphatic "No!", since no friend would refuse to help under such circumstances (the opening words in Greek occur elsewhere in Luke, but have no contemporary parallels, and I. Howard Marshall regards them as probably characteristic of Jesus himself). However, Jesus goes on to point out that even if friendship wasn't a big enough motivation, help would still be forthcoming. As with verses 9-13, the parable is therefore an incentive to pray. The parable of the Unjust Judge has a similar meaning.
Read more about this topic: Parable Of The Friend At Night