Musar for Kiddushin 139:18

טמא טמא יקרא . He shall call out (13,45) "Unclean! Unclean!" This is an allusion to the statement by our sages (Kidushin 70a) that כל הפוסל במומו פוסל, "When someone declares someone else as unfit, this usually reflects upon himself," i.e. that he suffers from a similar imperfection. When the Torah says in 21,18: כל איש אשר בו מום לא יקרב, "any person who is blemished must not draw near (the Tabernacle to perform sacrificial service)," this is because in principle the priest is to offer himself when he offers a sacrifice on someone else's behalf.

Be very careful concerning gossip for with this you shame yourself. For he who finds others unworthy is himself unworthy, and he does not speak in praise of anyone, and his way is to find people unworthy with the fault that he himself possesses (Kiddushin 70a).For this fault of his is constantly on his mind and when he gossips he expresses it with his mouth. For every man can be tested and recognized by his deeds. How? When you see a man who is accustomed to praise women and to speak of them always, know that he loves women. And if he praises good food and wine and does so constantly, know that he is a glutton and a drunkard And so is it with everything. And proof of this you may find in the verse, "Oh how love I thy law! It is my meditation all the day" (Ps. 119:97). Because I love the Torah, I always speak of it — since whatever a person loves in his heart, he lends to speak about always.