Theophylact of Ohrid — as excerpted in the Catena Aurea on Luke 18:1-8

“As if He said, If perseverance could melt a judge defiled with every sin, how much more shall our prayers incline to mercy God the Father of all mercies! But some have given a more subtle meaning to the parable, saying, that the widow is a soul that has put off the old man, (that is, the devil,) who is her adversary, because she approaches God, the righteous Judge, who neither fears (because He is God alone) nor regards man, for with God there is no respect of persons. Upon the widow then, or soul ever supplicating Him against the devil, God shews mercy, and is softened by her importunity. After having taught us that we must in the last days resort to prayer because of the dangers that are coming, our Lord adds, Nevertheless, when the Son of man cometh, shall he find faith on the earth?”