Then He said to them, “Suppose one of you has a friend, and goes to him at midnight and says to him, ‘Friend, lend me three loaves; for a friend of mine has come to me from a journey, and I have nothing to set before him’; and from inside he answers and says, ‘Do not bother me; the door has already been shut and my children and I are in bed; I cannot get up and give you anything.’ I tell you, even though he will not get up and give him anything because he is his friend, yet because of his persistence he will get up and give him as much as he needs.
Luke 11:5-8
Jesus taught the disciples on a number of occasions “that they should always pray and not give up” (Luke 18:1).