Luke 18:1, 6-8

Now Jesus was telling the disciples a parable to make the point that at all times they ought to pray and not give up and lose heart

Then the Lord said, “Listen to what the unjust judge says! And will not [our just] God defend and avenge His elect [His chosen ones] who cry out to Him day and night? Will He delay [in providing justice] on their behalf? I tell you that He will defend and avenge them quickly. However, when the Son of Man comes, will He find [this kind of persistent] faith on the earth?”