Contradiction with Matthew 6:7
This verse advises against using vain repetitions in prayer, which may seem contradictory to the idea of persistent praying in Luke 18:1.
Matthew 6:7: But when ye pray, use not vain repetitions, as the heathen [do]: for they think that they shall be heard for their much speaking.
Contradiction with Isaiah 1:15
This verse states that God may not listen when we pray if our hands are full of blood, suggesting that persistence alone might not be effective.
Isaiah 1:15: And when ye spread forth your hands, I will hide mine eyes from you: yea, when ye make many prayers, I will not hear: your hands are full of blood. [make...: Heb. multiply prayer] [blood: Heb. bloods]
Contradiction with Proverbs 28:9
Suggests that if one turns away from hearing the law, even their prayer is an abomination, implying persistence in prayer without righteousness is futile.
Proverbs 28:9: He that turneth away his ear from hearing the law, even his prayer [shall be] abomination.