To answer this question, it will help to understand why vows were instituted in the first place. Vows were instituted in Old Testament times in order to settle disputes because men were generally not honorable.
Their own words were not sufficient to the other party in critical situations. So, due to their general lack of integrity, the making of vows was implemented.
A vow is not something to be taken lightly. From the beginning, making a vow has been very serious business.
When a vow was made in God’s Name, His Name, reputation and integrity were put on the line. If what was promised in God’s Name was not fulfilled, then the one who made the vow was in sin. God was made to look bad to those who knew of it and the situation would become a stumbling block to those who did not know God. For that reason, a vow was entered into with extreme caution, so that God’s Name would not be defamed.
The best policy is to keep it simple and do what you say. Jesus said in Matthew 5:34-37: “‘You have also heard that our ancestors were told, “You must not break your vows; you must carry out the vows you make to the Lord.” But I say, do not make any vows! …Just say a simple, “Yes, I will,” or “No, I won’t.” Anything beyond this is from the evil one.’”
Your simple yes or no should be so filled with honesty and integrity that the one you are coming into agreement with will be able to see that you are a person of your word. You should not have to emphasize your words with other words, such as a promise, pledge or vow.