The Gemara brings: a person should not let a disgraceful thing out of his mouth. This is derived from that which the Torah changed to write the words “אשר איננה טהורה, that which is not tehorah,” in place of the shortened and standard way of writing, with a lashon “טמאה, defiled.” Rashi explains, in place of writing the word “הטמאה, the defiled,” which is 5 letters, the Torah writes in an indirect way אשר איננה טהורה, which is 13 letters. The Torah adds 8 extra letters to specify the defiled animal in a nice way. Although the Torah does state the lashon טמא elsewhere, in one place the Torah teaches that a person should try to speak in a nice way.
Rabbeinu Yonah explains differently, the Torah is specifically concerned here to not write טמאה, because by Noach’s time, it was permitted to eat a defiled animal, but it was not tehorah for a korban. Therefore, if a person would speak in a derogatory way about that which he eats and benefits from, it is considered something disgraceful. Similarly, the Gemara brings: where do we know this thing that people say, “A pit that you drank from do not throw into it a clump of earth?” Rashi explains, where do you know that you should not disgrace something which you needed to use? The Gemara proves this from that which it states לא תתעב אדומי כי אחיך הוא ולא תתעב מצרי כי גר היית בארצו, do not make an Edomi detestable, since he is your brother, and do not make a Mitzri detestable, since you dwelled as a stranger in his land.” The Maharsha adds, although it is fitting to make a Mitzri detestable since they threw the males into the river to kill them, still in all, they hosted you in their land.
We see that a person is obligated to lengthen his speech, in order not to say something disgraceful about that which someone benefited from. Says Rabeinu Yonah, this is like a fence to be careful from speaking nivul peh, lashon hara, and other inappropriate things.
The Gemara brings; one of the Kohanim said to Rebi Yochanan ben Zakai, “I received my portion from the lechem hapanim as the size of the tail of a lizard.” They checked after him and found out about him that he was a shemetz pessul. Rashi explains he was a chalal, which is the child of a Kohen who is born from an improper marriage, and is passul for Kehuna. Tosfos brings b’shem Rabeinu Chananel that this person worshiped idolatry, from the lashon לשמצה בקמיהם, and passuls a Kohen from doing avodah. The Yad HaKetanah says, we see from this Gemara that just with speech alone – by hearing how one talks, it is noticeable what type of person he is; whether for good or bad.
The passuk states in Mishley, “ואיש לפי מהללו, and a person according to his praise.” Rashi explains a person is evaluated by the way people talk about him. If people praise the person’s actions, it reflects that he has good character traits. Whereas if people reprimand the person’s actions, it reflects that he has bad character traits. I heard another explanation: according to the praise that a person says about others is how he himself is. If he speaks good about others, then it reflects he too has good character traits, and vice-a-versa.
Let us be careful with what we say to speak in a nice way which will reflect good character.