Jesus taught his disciples that when speaking their “yes” was to be “yes” and their “no” was to be “no”. He went on to explain that if they made a vow it was valid and to be kept. Later when addressing the religious leaders of his day, he rebuked them for their teaching the people that if they made a vow on the temple it was invalid, but if they made it on the gold in the temple it was valid. Jesus pointed out that they were foolish, because it was the temple itself that made the gold in it holy. In other words, Jesus showed them that if they made an oath it was to be honored.
Jesus’ teaching implies that we have a problem with our speech. It raises the question of “why”? Why should we ever need to make a vow or an oath? Could it be that our “yes” doesn’t always mean “yes”? Sometimes we have to make a promise or take an oath, to communicate to others that this time we really mean “yes”. That is a problem. Have you ever noticed that throughout the Gospels, we never see Jesus making an oath or a vow? Jesus never had to because everyone who heard him speak knew that he always spoke the truth, so that an oath was unnecessary or redundant. When Jesus told us to let our “yes” be “yes” and our “no” to be “no”, he meant for us to live in a manner similar to the way he lived.