A single saying standing between the prayer and the four generations.
Quick answer
Do not carry a bad report about someone to the person who has power over them. The reason given is that the wronged servant has one recourse left, and it will find you.
Read both lines
The first line names a specific act, not gossip in general. תַּלְשֵׁן is to use the tongue against someone, and the direction is what makes it dangerous: upward, to the one person whose opinion decides the servant's life. A servant slandered to his master cannot correct the record. He has no standing in that conversation and no way into it.
The second line says what he does have. He curses, and the curse lands, and the person who spoke is found guilty, the same verb the sacrificial law uses for incurring real guilt rather than feeling bad. The saying does not appeal to the slanderer's conscience or to the master's fairness. It says the powerless man is not as unprotected as he looks.
What it does not mean
This is not a rule against reporting genuine wrongdoing, and it must never be used to keep someone quiet about harm. The verse is aimed at the person with access using it against a person without any. Someone speaking up about abuse, theft, or danger is doing the opposite of what this forbids, because they are not exploiting an asymmetry, they are exposing one. Where a proverb about holding your tongue is being used to protect a powerful person from the truth, the proverb is being used backwards.
Related: Proverbs 29:21 · Proverbs 17:2 · Proverbs 22:22–23
New King James Version®, Copyright © 1982, Thomas Nelson. All rights reserved. Full copyright information. Scripture provided by API.Bible.
Go Deeper
If this verse has been used to put weight on you that it was never carrying, ask about it directly.