Our Gemara on Amud Aleph quotes the verse in Koheles (5:4): “It is better not to vow at all than to vow and not fulfill.”

There is a beraisa that takes it one step further, advocating that it is best not to make a vow at all (Nedarim 9a):

“Better that you should not vow than that you should vow and not pay”

(Ecclesiastes 5:4); better than both this and that is one who does not take a vow at all. This is the statement of Rabbi Meir. Rabbi Yehuda says: Better than both this and that is one who vows and pays.”

There are different interpretations of this Beraisa, but the halachic consensus is that, generally speaking, vows are to be avoided—even with full intention to fulfill them—except when there is a reason that the benefit outweighs the risk. Shulchan Aruch (YD 203:4–6) codifies it as follows:

“One should be careful not to vow in any matter. Even tzedaka should not be vowed; rather, if one has what to give, they should immediately give it, and if not, they should not vow until they have it…”

“In a time of distress it is permitted to vow.”

A person who says, “I will learn this perek,” and is afraid lest they become negligent in this matter—it is appropriate for them to vow in order to inspire and commit. And so, if one is afraid that their inclination will attack them and they will transgress any negative commandment, or become negligent in the fulfillment of a positive commandment, it is a commandment for that person to vow in order to inspire themselves.

What is the psychological upshot of this? On the one hand, overcommitting is not a healthy process. The righteous do much but say little (Bava Metzia 87a). But why is this so? Psychologically, a person can be in conflict. One’s conscience tells him that he should do something, or more primitively he has a wish to be seen as good and it tells him he should be good, but he also may not want to for other self-serving reasons—to relax or indulge. There is an internal struggle and gridlock. When there is conflict, an externalizing voice helps overpower the conflict and enact the decision. If the person is struggling but largely inclined toward doing the moral or long term choice, the external voice—vow or even expression—helps finalize the decision. But if the larger part of the will is to be morally lazy, the expression of the words does not galvanize action. In fact, sometimes it is even counterproductive, because the exteriorizing of the motivation allows for an illusion of compliance. The person might ease their conscience temporarily by committing, but deep down it is an empty promise, and when the time comes to deliver, there will be procrastination and avoidance.

This is how complex human motivation and emotions are. There are authentic conflicting drives within most people. When one uses speech, which is a form of turning thoughts into action, it is a double-edged sword. In the right way, it can seal the deal and tip the internal scales toward doing the right thing. However, if the commitment level and drive are low and the ability to rationalize is high, verbally committing becomes a way to avoid actually doing it and is literally empty promises.