Musar על בבא קמא 198:18

We next have the injunction not to go about slandering people (19,16) This is also directed at judges. It includes a judge who did not preside over a certain litigation and who says that if he had been the judge in that case the decision would have been different. When the Torah phrases this injunction as "do not walk…" it is an allusion to people who are in the habit of going from one house to another exchanging gossip, etc. The Torah suggests to such people that if they do not want to become guilty of slander they should not keep "walking" around so much. Staying at home is a self-imposed "fence" around this law.