Titus 1:9; Titus 2:6; Titus 2:15

9 holding fast the faithful word which is in accordance with the teaching, so that he will be able both to exhort in sound doctrine and to refute those who contradict.
6 Likewise urge the young men to be sensible;
15 These things speak and exhort and reprove with all authority. Let no one disregard you.