Luke 2:37
and then being a widow even for fourscore and four years. She departed not from the temple, but worshiped with the fasting and prayer, night and day.
Luke 11:8-13
"I tell you that, though he will not rise and give to him because he is his friend, yet because of his importunate persistence he will rise and give him whatever he needs.
Luke 18:7
"And will not God see justice done to his elect who are crying unto him day and night, even if he seems to delay helping them?
Ephesians 6:18
Continue to pray at all times, with all prayer and supplication in the Spirit, and watching for it with all perseverance and supplication for all saints;