Another mitzvas aseh that a person could easily violate when he speaks lashon hara is “וּמִקְדָּשִׁי תִּירָאוּ”. Almost all the Rishonim count it as a discrete, separate mitzvas aseh to fear a mikdash, to fear obviously the Beis Hamikdash, the Mishkan, but that applies even to our shuls. We are obligated to treat our shuls with great respect. And, explains the Chafetz Chaim, if I’m in this holy place, if I’m in G-d’s house and I’m violating G-d’s words right here I’m defaming, I’m debasing a Jew right here, what I’m doing is clearly not fearing the mikdash, I’m not fearing the shul.
Meaning, if I’m standing outside, if I’m in a ball field and I’m talking about Reuven, so it’s one issue called “לֹא תֵלֵךְ רָכִיל בְּעַמֶּיךָ” and everything associated. But if I’m doing that in shul then additional to everything else that I’m potentially violating, I’m certainly not acting with the proper decorum, with the proper respect and with the proper fear for a shul. And almost always if you’re going to speak lashon hara in a shul you violate this as well.
And explains the Chafetz Chaim that unfortunately this is very common. Oftentimes that’s when we meet our friends, maybe Shabbos, maybe in the morning by Shacharis or by Mincha, whenever it may be. That’s when we congregate, that’s when we speak to people and oftentimes it becomes a hotbed of lashon hara. And again, aside for the issues of “לֹא תֵלֵךְ רָכִיל בְּעַמֶּיךָ” and all of the lo sa’asehs and asehs, additionally we are potentially violating “וּמִקְדָּשִׁי תִּירָאוּ”, not fearing a shul, not acting with the proper decorum and respect. And I could potentially have violated that mitzvas aseh myself.