Luke 18:1
Then Jesus told His disciples a parable for the purpose of showing them that they should pray continually and not become discouraged.
Luke 18:7
So, will God not grant justice to His elect [i.e., His people] who call out to Him [i.e., in prayer] day and night? Will He be slow in helping them?
Ephesians 6:18
[Then] offer all kinds of prayers and requests in [harmony with] the Holy Spirit at all times, and be alert constantly in making requests for all the saints [i.e., God's holy people].
Hebrews 10:36-37
For you need to be steadfast so that, after you have done what God wants, you will receive the promise [of an inheritance. See 9:15].