Luke 2:37
She was very old; from girlhood she had lived seven years with a husband, and now had been a widow eighty years. She never left the temple, but continued to worship all day and all night with fastings and prayers.
Luke 11:8-13
I tell you, although he will not get up and give you any because he is your friend, yet because of your persistence he will get up and give you all your needs.
Luke 18:7
And will not God give justice and protection to His chosen people who continue to cry to Him day and night, since He is so patient with them?
Ephesians 6:18
Keep on praying in the Spirit, with every kind of prayer and entreaty, at every opportunity, be ever on the alert with perfect devotion and entreaty for all God's people,