“Modesty and faith are connected with one another just like two things fastened by a rope. If one of them is gone, the other is also lost” [1]. Imam Baqir (AS). Modesty is a special sense that prevents one from saying inappropriate words and making mistakes. It refers to an uncomfortable feeling accompanied by embarrassment, caused by one's anxiety about being exposed to some unworthy or indecent conduct. This concept, as one of the highest and most fundamental moral qualities, is known as Haya in Islam. Modesty in Islam describes shyness and shame, but Haya represents a more profound implication that is based on faith. In many sayings (Hadiths), it has been quoted that modesty is linked with faith and originates from it [1, 2]. Hence, it is one of the most important characteristics that every Muslim should acquire and possess [3]; particularly Muslim women (“haya is a good characteristic for all, but is better for women” [4]).

Modesty in Islam: natural and acquired

There are two types of modesty: natural and acquired. An example of the former is the feeling of shyness and humility naturally occurring in a young child that makes him/her cover the private parts of the body from others. Or, in the story of Eve and Adam (PBUT) where they realize their nakedness and try to hide their genitals. This kind of modesty is common sense that exists within all human beings, believer or non-believer: “God Almighty divided the modesty among people just as He divided the provision” [5], and what differentiates them from animals: “If modesty did not exist … the promises wouldn’t be kept … Nobody would do any good, and nobody would refrain from the evil … if it weren’t for modesty, many people wouldn’t stop sinning.” [6]. Modesty serves as a cover on the soul that conceals the defects and calms down wrath and lust [7]. No one can, therefore, justify his/her sins and mistakes because of not being naturally given a sense of modesty.

The latter, on the other hand, can be only attained as a result of knowing and perceiving the Glory of Allah and minding His presence everywhere and in every second. In Islamic ethics, modesty is more than just a question of how a person dresses and acts in social interactions; instead, it is reflected in a Muslim’s conduct before God, before others, and even when one is alone.

Modesty towards others

Modesty towards others entails that one has decent and reasonable behavior in public, avoids indecent talks and vain activities, and respects everyone around him/her. If one has developed this ethical aspect within him/her and obeyed this sense, he/she will become ashamed when someone notices him doing something wrong. This feeling will be even worse when the other person is in a higher position. This, consequently, stops him/her from repeating that action.

To clarify the importance of modesty towards people, Imam Ali (AS) said that the evilest of all is who is not ashamed of his actions in front of people [8].

Modesty towards others includes especially the opposite gender and involves not gazing at them [9], harming them in any way or indulging in any forbidden (Haram) relation with them. In Surah Nur, Allah guides both men and women to the key to modesty by saying that believing men and women should lower their gaze and guard their modesty (24:30-31).

A good instance of modesty in the interactions between opposite genders is described in Surah Qasas, verses 23-26, between the daughters of Shoaib (PBUH) and Moses (PBUH). These verses demonstrate that the daughters of the prophet work and appear in society, but they care about how they interact with others; they concentrate on what they should do without having unnecessary dialogues with men. They communicate as much as necessary, with respect and dignity. Their speech is direct and clear-cut with Moses, so are Moses’s words. Even the way they both walk is with care and shyness [10].

Modesty towards Oneself

Modesty towards oneself means that a person treats himself fairly in private. It is caused by the unpleasant feeling that arises when thinking of or doing something improper which consequently stops one from forbidden (Haram) thoughts or illicit acts. It was mentioned that when one does something indecent and suddenly notices the presence of others, he becomes ashamed (if he still possesses the natural modesty that is laid within his soul); a higher level of Haya is being ashamed of oneself when no one else is present. This kind of modesty is known as the yield of faith: “The shame a person feels from himself originates from [his] faith.” [11].

Modesty towards God

Modesty towards God is called the best level of modesty [12]: “be modest in front of Allah for He has a right to your modesty” [13]. To accomplish this, one should first believe that nothing can be concealed from God “Does he not know that Allah sees [him]?” (96:14). In fact, Allah sees and knows everything, and is closer to humans more than themselves: “and We are nearer to him than [his] jugular vein” (50:16). Consequently, a modest person toward God will avoid any indecent act, in public or private, and will leave sinful thoughts behind.

References:

1. M. al-Kulaynī, “Al-Kafi”, vol. 2, p. 106.
2. M. B. Majlesi, “Bihar al-Anwar”, vol. 75, p. 309.
3. M. al-Kulaynī, “Al-Kafi”, vol. 2, p. 106, T. 5.
4. A. Q. Payande, “Nahj Al-Fasahah”, p. 578, T. 2006.
5. S. H. al-Amili, “Wasail al-Shia”, vol. 20, p. 135.
6. M. B. Majlesi, “Mofazzal monotheism”, Chapter: Human Senses.
7. “Nahj al-Balagha”, no. 223
8. “Ghurar Al-Hikam”, no. 5464
9. M. B. Majlesi, "Bihar al-Anwar”, vol. 101, p. 40.
10. N. Makarem Shirazi, “Tafsir Nemooneh”, vol. 16, p 58-59.
11. “Ghurar Al-Hikam”, no. 4944.
12. “Ghurar Al-Hikam”, no. 5451.
13. H. T. Nuri Ṭabarsi, “Mustadrak al-Wasail”, vol. 8, p. 462.

Imam Sadiq (AS) is the sixth Shiite Imam after his father Imam Baqir (AS). The Shiite school is mostly famous as “Jafari School” because Imam Sadiq (AS) played the most important role among the other Imams in explaining and spreading the Shiite teachings. Most of the Shiite hadiths are narrated from Imam Sadiq (AS). 

Enlightening people about the essential message of Islam

Some Islamic teachings and practices are considered as the outer aspect of Islam, like praying, Hajj, Zakkat and stuff like that. These are the practices which any Muslim should do and respect but all of them have a deeper meaning and a concealed message that people mostly do not get. Sometimes people get so much used to do these practices and conduct ceremonies that they forget about the original meaning of them. 
The holy Prophet (PBUH & HP) says: 
O Aba-Zar! (One of the companions of the Prophet) Allah almighty doesn’t care about your faces or your wealth, but he cares about your hearts and your actions (1)
When you pray or pay your Zakkat, it must change you and teach you that praying is for getting closer to Allah and Zakkat is for helping the needy. 
In this regard the holy Quran says:
Did you see him who denies the Religion?  That is the one, who drives away the orphan, and does not urge the feeding of the needy.  Woe to those who pray but are heedless of their prayers —who show off but deny aid. (The Holy Quran 107:1-7)
Imam Sadiq (AS) in different prayers says that if you pray but still feel pride and vanity, it will be useless for you because the Satan himself prayed for Allah for 6000 years but due to his vanity and jealousy, he couldn’t stand the greatness of Adam and tried to deceive him and Allah cursed the Satan. 

Being Kind with the ones who disagree 

Once Mufazzal ibn Umar (One of the brilliant pupils of the Imam) was sitting in the Mosque of the Prophet (PBUH & HP) in Medina. Then he saw Ibn Abi al-Ouja (one of the Atheist Philosophers) who was insulting the Prophet in the mosque and telling lies to the people saying that there is no god. 
Mufazzal says that this made him so angry and he couldn’t control himself so he shouted: “O enemy of Allah! Have you become atheist and denied the God who created you?”
Ibn Abi al-Ouja replied: “If you are one of the religious scholars, I will have debate with you and if you are not, our discussion will be in vain. But if you are one of the companions of Jafar ibn Muhammad (Imam Sadiq) you must know that he wouldn’t talk to us like that and he wouldn’t have discussion with us in this way. He has heard so many more disgraceful words from us but he never has insulted us. He is so knowledgeable, patient and wise and he wouldn’t lose his control out of anger, ignorance or animosity. He always listens to us.” (2)
Imam Sadiq (AS) is famous for his numerous debates with the Sunnis, Atheists, Jews, Christians and so forth, but he would never insult them. He always would order his followers to be kind with the people. 
For example about the Sunnis Imam Sadiq (AS) says:
Participate in their funerals and visit them when they are sick, and give them their rights because if a person among you is pious, honest, trustable and good-tempered, people would say “this is a follower of Jafar” and this makes me happy! (3)

Imam Sadiq (AS) and Caring about the young people

Once Imam Sadiq (AS) asked one of his pupils who had gone to Basrah (a city in Iraq):
“How was the enthusiasm of the people for our message and converting to Shia?” Imam Sadiq (AS) asked.
He said: “The ones who want to listen to our message are so few. Some of them did but they are few”
Imam Sadiq (AS) said: “You must talk to the young ones, because they are more eager for finding everything good.” (4)
Imam Sadiq (AS) also says:
“Teach hadiths to your young children from their childhood before the time that others beat you in training them” (5)
Young Shias must set Imam Sadiq (AS) as a pattern for themselves and follow him. They should learn more and more so that the different people who have gone astray can’t deceive them. 

Resources 

1.  Al-Amali, Sheikh Toosi, Pg.536
2.  Tohid al-Mufazzal
3.  Kafi, Koleini, vol.2, pg.636
4.  Vasail ash-Shia, vol.11, pg.448
5.  Kafi, Koleini, vol.6, pg.47