This is certainly good advice. It is warning the reader about the dangers of giving in to jealousy, and that selfish ambition born of envy, wanting to even up the perceived difference in favor of the self, and perhaps even surmount and outdo the perceived opposition in the contest. In actuality, that contest, in which the jealous individual does not feel they measure up, is a self-generated and self-created perception that will never be realistic and accurate. After all, the feeling of jealousy itself is based on a dark inner feeling of dislike, in seeing someone outdoing the person or outshining them, and beginning to resent the unequal status. This often creates a situation where people will engage in lying, or a distortion in some way, to minimize the perceived shortcoming that is bothersome. But in doing so, the person is, in a sense, walking out on a limb further and further because in lying they risk exposure, and not only will their attempt at compensation fall apart, they will be exposed with a very intense focus on what they self‑reveal is a contrast between the object of envy and themselves. The very last thing they would want to see happen as their strategy of lying is meant to cover up what is making them uncomfortable to, in effect, hide it from view.
So this is good advice meant to help protect people from themselves, to guide them towards a better course of action so as not to compound the damage from being out of alignment and giving in to jealous feelings. When one adds another emotional misalignment that is a kind of transgression in the bargain, it becomes a wider error and, in fact, a defect. While jealousy is simply a person’s perspective they are being outdone by someone else’s attributes, lying is an overt act putting them on record through their intentions to manipulate and deceive others. When the likelihood is, what their jealousy is making them worry about in terms of their own shortcomings, may not even be noticed by others and it is almost certainly the case others will not care if they even share similar standards in evaluating the issue of concern and its very nature. After all, most people do not go around judging others on superficial characteristics, often the cause of jealously, like attractiveness or having personal possessions that might be accoutrements of accomplishment and a kind of status symbol. So someone who goes out of their way to try to falsely build themselves up through a false narrative will, in fact, by lying, expose themselves to be the lesser person and greatly worsen their situation because then they will be dealing with two difficulties—the perceived shortcomings making them jealous, and having been called out by someone catching them in a lie.