What is Mussar (Discipline)?
The word Mussar appears in Tanakh (Hebrew Bible) 51 times, more than half of them in the book of Proverbs. It carried a connotation of ethical instruction according to the teachings of the Torah.
In the rabbinic period, texts such as Pirkei Avot carried the thread of personal ethical teachings. For example: “If I am not for myself, who will be for me? If I am only for myself, what am I? And if not now, when?” Pirke Avot 1:14 (MJL)
What is a middah (character-trait) - what are middot?
To assist us on our personal spiritual curriculum, Mussar teaches us to strive toward the positive and strengthen the opposite of the trait with which we struggle. So, for example, if you tend to be miserly, generosity would be on your personal curriculum. A judgmental person (one who judges others) would work on the trait of honor (honoring every human being), and so on through the full range of middot. (RJ)
What distinguishes us from one another is not that you have one trait and I have another, but rather the degree or measure of the traits that exists in each of us. (Ohef Sholom)
What do I do with these middot?
According to some schools of mussar there are three parts to a daily practice: a morning mantra that is read out loud or chanted to set one’s focus on refining that trait in the day ahead, a mindful action as one goes through the day, and then nightly journaling. (MJL)
Source #1 - Listen Up to this Information (Listening as Obligation)
(ד) שְׁמַ֖ע יִשְׂרָאֵ֑ל יקוק אֱלֹקֵ֖ינוּ יקוק ׀ אֶחָֽד׃
(4) Hear, O Israel! The LORD is our God, the LORD alone.
Why the specific instruction to listen? What is the nature of this information that we should listen to?
Listening is an act of validating the other, says the Mishkan Tefila siddur:
The "ayain" at the end of Shema (שְׁמַ֖ע) is traditionally enlarged in the siddur and the "dalet" at the end of Echad (אֶחָֽד) is traditionally enlarged also. These two highlighted letters spell the word (ed) meaning 'witness'... when we listen to certain information, we make it real. God will indeed be ours and universally one.
Source #2 - Allow Me to Listen to You (Listening as an [overwhelming] privilege)
(14) “O my dove, in the cranny of the rocks, Hidden by the cliff, Let me see your face, Let me hear your voice; For your voice is sweet And your face is comely.”
(18) Moses said, “Oh, let me behold Your Presence!” (19) And He answered, “I will make all My goodness pass before you, and I will proclaim before you the name LORD, and the grace that I grant and the compassion that I show. (20) But,” He said, “you cannot see My face, for man may not see Me and live.” (21) And the LORD said, “See, there is a place near Me. Station yourself on the rock (22) and, as My Presence passes by, I will put you in a cleft of the rock and shield you with My hand until I have passed by. (23) Then I will take My hand away and you will see My back; but My face must not be seen.”
Source #3 - Listening as an Skilful Art (Listening as a Challenge - Being Open to Conflicting Opinions)
אף אתה עשה אזניך כאפרכסת וקנה לך לב מבין לשמוע את דברי מטמאים ואת דברי מטהרים את דברי אוסרין ואת דברי מתירין את דברי פוסלין ואת דברי מכשירין
So too you, the student, make your ears like a funnel and acquire for yourself an understanding heart to hear both the statements of those who render objects ritually impure and the statements of those who render them pure; the statements of those who prohibit actions and the statements of those who permit them; the statements of those who deem items invalid and the statements of those who deem them valid.
וּלְהַגִּיד גְּדֻלָּתוֹ שֶׁל הַקָּדוֹשׁ בָּרוּךְ הוּא, שֶׁאָדָם טוֹבֵעַ כַּמָּה מַטְבְּעוֹת בְּחוֹתָם אֶחָד וְכֻלָּן דּוֹמִין זֶה לָזֶה, וּמֶלֶךְ מַלְכֵי הַמְּלָכִים הַקָּדוֹשׁ בָּרוּךְ הוּא טָבַע כָּל אָדָם בְּחוֹתָמוֹ שֶׁל אָדָם הָרִאשׁוֹן וְאֵין אֶחָד מֵהֶן דּוֹמֶה לַחֲבֵרוֹ
(5) And this serves to tell of the greatness of the Holy One, Blessed be He, as when a person stamps several coins with one seal, they are all similar to each other. But the supreme King of kings, the Holy One, Blessed be He, stamped all people with the seal of Adam the first man, as all of them are his offspring, and not one of them is similar to another.
Source #4 - When Listening becomes a Liability (Complicit in Event)
In the West, Eretz Yisrael, they say: Third speech, i.e., malicious speech about a third party, kills three people. It kills the one who speaks malicious speech, and the one who accepts the malicious speech when he hears it, and the one about whom the malicious speech is said.