Titus 1:9-10 English Standard Version (ESV) 9 He must hold firm to the trustworthy word as taught, so that he may be able to give instruction in sound[a] doctrine and also to rebuke those who contradict it. 10 For there are many who are insubordinate, empty talkers and deceivers, especially those of the circumcision party.
2 Peter 2:1 ESV But false prophets also arose among the people, just as there will be false teachers among you, who will secretly bring in destructive heresies, even denying the Master who bought them, bringing upon themselves swift destruction.
