1)
What is evil of the tongue?
1.
Radak: It is speaking bad about people, including false testimony, cursing one's father or mother, a judge or a king 1 , and all the more so blasphemy.
1
Surely cursing any Kosher Yisrael is evil! (PF)
2)
What is "Mirmah"?
1.
Radak: It is speaking with the mouth unlike what is in his heart. He is Merameh (deceives) his colleague - he speaks good to him, and plots evil in his heart - "b'Fiv Shalom Es Re'ehu Yedaber uv'Kirbo Yasim Arbo" (Yirmeyah 9:7). This is a Lav of the heart - "Lo Sisna Es Achicha bi'Lvavecha" (Vayikra 19:17).
