Among the garments of the Kohen Gadol (the High Priest) we find that the robe which he wore contained many small bells at its hem. Midrashim and commentaries inject meaning into the use of these bells, but the verse itself states their purpose: “And he shall wear it while serving, and its sound shall be heard when he enters the sanctuary before Hashem, and when he exits, lest he die” (28:35). The purpose of the bells was to make a sound, alarming anyone who was present that he is coming, and they should allow him to do the service. But why, then, does the verse specify the sound’s importance when he is leaving? What utility of service does it achieve once his work is already finished (See Ramban)?
The Midrash (Vayikra Rabbah 10:6) tells us that each element of the Kohen’s garb was meant to atone for certain sins. These bells were meant to atone for improper speech, a sound for a sound. The Gemara (Taanit 8a) illustrates an interesting metaphor for one who speaks poorly of another: In the future, all animals will approach the snake (which represents evil speech) and ask: ‘the lion mauls and then eats its prey… but what benefit do you derive from poisoning someone?’ The same is true for a slanderer- While it may feel good in the moment, the sin of speech is worse than others because it provides no tangible, material benefit to the offender.
It’s true- the Kohen’s bell-noises provide him no utility when he exits the Sanctuary. But that’s exactly the point. To combat the problem of improper speech, the bells do something which provide no material benefit. They are simply there -on the way out- to notify others that they can return to their work. While the Kohen gets nothing, only others benefit. This is the exact opposite of the slanderer. This is the pernicious nature of slander, but it’s also the praiseworthy quality of truly good deeds. The more we can contribute on behalf of another without any personal benefit, the more laudable –and audible– that deed becomes.