The antonyms for the phrase "violate oath" would be "keep oath," "honor oath," "uphold oath," "obey oath," or "fulfill oath." These words all imply a sense of duty and loyalty towards the oath taken, and the idea of breaking that oath is completely opposite to the meaning of these words. Keeping an oath is important for maintaining personal integrity, trustworthiness, and moral character. When someone keeps their oath, they maintain their credibility and reputation, which is essential for professional and personal relationships. Upholding an oath shows a strong sense of devotion to one's beliefs and principles, which is admirable and respected by others.