REFRAINING FROM LOQUACITY
Shaykh Tusi (sanctified be his spirit) narrates from the Holy Prophet (s) that he said:
Do not overindulge in speech that concern other the remembrance of God, for overindulgence in speech about other than the remembrance of God results in the hardness of the heart (qasaawat al-qalb), and the most remote one from Allah among the people is one who has the hardness of the heart. 
Shaykh Tusi has put this tradition as the very first tradition of his [well-known] work Amaali, and this shows his special attention to it as well as the subject.
Al-Kulayni (sanctified be his spirit) likewise has narrated this tradition from Imam al-Sadiq (‘a) but with a slight variation. He narrates that Imam al-Sadiq (‘a) said:
Hadhrat Masih [Prophet ‘Isa (‘a)] would say:
Do not overindulge in speech about other than the remembrance of God, for those who overindulge in speech about other than the remembrance of God become hard and stone –hearted, despite their ignorance [about the same]. 
Narration of Presence
10. A Session of Silence
Hadhrat Ustaad (perpetual be his esteem) indeed [constantly] practices this instruction. His speech would be well-calculated and brief, yet profound [and full of meaning]. In the class he would refrain from marginal speech and rhetoric of beauty, and would speak selectively, and indulge in sublime matters. He is truly an example of the following poem:
Kam gooy o guzide gooy chun durr
Taa ze andake tu jahaan shawad pur
Speak less and selectively [and be] like a pearl
So that with little of you, the world becomes full
One of the great lessons we learnt from years of being in the presence of Hadhrat Ustaad ‘Allama Hasan Zadeh Amoli (perpetual be his high esteem) was his silence and selective speech. On his arrival in class a halo of silence would prevail the gathering; and between his arrival and the official beginning of the lesson the gathering for a few minutes would be that of silence.
11. The mouth is a Door of Allah
That [particular] day Hadhrat Ustaad gave an admonition to the wayfarers of the alley of amorous love (‘ishq) and Divine knowledge and said:
The mouth is a door of Allah! Control its exports and imports; the mouth is the ear of the spirit; strive to make your intellect control your mouth.
12. The Best Response
[Above: A photo of 'Allama al-Tabataba'i]
One of the students of Hadhrat Ustaad (perpetual be his esteem) in this connection says:
The wise philosopher, ‘Allama Hasan Zadeh Amoli (perpetual be his high esteem) has narrated that whenever someone would travel with Marhum ‘Allama Tabataba’i, as long as he would not ask anything from ‘Allama, the latter would not speak to anyone.
And it must be known that one should not respond to every question, and this depicts one’s knowledge and awareness.
One day in the class of the venerated Ustaad ‘Allama Hasan Zadeh Amoli (perpetual be his high esteem) from whose grace of knowledge I was benefiting, a person asked the Ustaad a question to which he responded saying: “Very good.” Then, when the class came to an end, the person said to the Ustaad: Is “Very good” also an answer? ‘Allama said: Yes, and it was the best answer! 
To be continued soon Insha Allah...