In the Gospel of Luke (chapter 18) Jesus tells a story about a destitute widow who had experienced a grave injustice. In the culture of her day women weren't typically allowed to plead their case in court. When women such as this had problems a male family member had to go before the judge to present their case. The fact this woman went before the judge all by herself indicated that she was all alone with no one to speak on her behalf.
Jesus tells us two things about the judge. He doesn't respect God and he doesn't care about people. Those are the two motivations for a judge to render a just decision, but in this case he has no incentive to render a just judgement. He's a selfish, narcissistic leader with no reason to come to the woman's defense.
But she wears him down by coming before him day after day begging for justice against her adversary, and the corrupt judge finally relents and grants her request.
This is a parable of contrast. It's also called a lesser/greater parable, if this lesser thing is true, how much more is this greater things true.
Luke tells us up front what the parable is about. "Then Jesus told his disciples a parable to show them that they should always pray and not give up." Luke pairs the following two ideas together, never give up and always pray.
Jesus closes the parable with these words. "And will not God bring about justice for his chosen ones, who cry out to him day and night? Will he keep putting them off? I tell you, he will see that they get justice, and quickly. However, when the Son of Man comes, will he find faith on the earth?”
If an unjust judge responds to a plea for justice because a destitute widow wears him down, how much more will our loving heavenly father hear our cries against the injustices in our word.
Facing injustice? Always pray. Don't give up.