In Lk.18 Immanuel-Christ-Jesus spoke a parable of the widow, and the unjust judge. This is a good warning of many unjust judges. Examples of good judges is cited in Ex. 18. However, this parable is Not about the unjust judge.
Men (mankind) ought to always pray, and not faint (lose heart, become discouraged).
"Avenge me of mine adversary."
After a while the unjust judge moved on the widow's behalf.
And shall not GOD avenge HIS Own Elect, which cry day and night unto HIM, though HE bear long with them?
I tell you that HE will average them speedily.