One should rigidly control his mind
Srimad-Bhagavatam
SB Cantos 10.14 to 12 (Translations Only)
SB 11.3.26, Translation:
One should have firm faith that he will achieve all success in life by following those scriptures that describe the glories of the Supreme Personality of Godhead, Bhagavān. At the same time, one should avoid blaspheming other scriptures. One should rigidly control his mind, speech and bodily activities, always speak the truth, and bring the mind and senses under full control.