Luke 11:8-10
I say to you, though he will not rise and give him because he is his friend, yet because of his importunity he will rise and give him as many as he needeth.
Luke 18:1
And he spoke a parable to them to show that they ought to pray always, and not be fainthearted:
Ephesians 6:18
praying with all prayer and entreaty at all times in the Spirit; and watching to this end with all perseverance and entreaty for all the saints,
Colossians 4:2
Persevere in prayer, being watchful therein with thanksgiving;
1 Thessalonians 5:17
Pray without ceasing;
James 5:16
Confess your trespasses to one another, and pray for one another, that ye may be healed. The earnest prayer of a righteous man availeth much.