Luke 11:8-10
I tell you, even though he will not get up to provide for him because of his friendship, yet because of the man's persistence, he will get up and give him as much as he needs. . . .

Luke 18:1
Then Jesus told them a parable about their need to pray at all times and not lose heart:

Ephesians 6:18
Pray in the Spirit at all times, with every kind of prayer and petition. To this end, stay alert with all perseverance in your prayers for all the saints.

Colossians 4:2
Devote yourselves to prayer, being watchful and thankful,

1 Thessalonians 5:17
Pray without ceasing.

James 5:16
Therefore confess your sins to each other and pray for each other so that you may be healed. The prayer of a righteous man has great power to prevail.