The Holy Prophet [s] said: "He who grieves a true Muslim cannot then compensate for it by offering him the entire world because it is not sufficient compensation (unless he repents and appeases the said person)."
Bihar-ul-Anwar, vol. 75, p. 150

Imam Kadhim [a] said: "Among your most compulsory duties towards your Muslim brother is that you conceal nothing from him which profits him either in this life or in the Hereafter."
Bihar-ul-Anwar, vol. 2, p. 75

Imam Hassan, the second Imam [a], said: "Treat others similar to the way you would like for them to treat you."
Bihar-ul-Anwar, vol. 78, p. 116

Imam Amir ul Mu'mineen Ali [a] said: "May Allah have mercy upon the person who services a right and removes a wrong, or refutes an injustice and establishes justice."
Ghurar-ul-Hikam, p. 181

Imam Sadiq [a] said: "These four characteristics are from the manners of Prophets [a]: righteousness, graciousness, patience and perseverance in tolerating misfortunes, and rising for the right of a believer."
Tuhaf-ul-Uqul, p. 277

Imam Amir-ul-Mu'mineen Ali [a] said: "Surely, it is the common people of the community who are the pillars of the religion, the power of the Muslims and the defence against the enemies. Your leaning should therefore be towards them and your inclination with them."
Nahjul Balagha, Letter 53

Imam Sadiq [a] said: "In no way is Allah worshipped better than by fulfilling the right of a believer."
Al-Kafi, Vol.2, p. 170

The Holy Prophet [s] said: "He who hurts a Muslim believer, surely he has hurt me."
Bihar-ul-Anwar, vol. 67, p. 72

The Holy Prophet [s] said: "He who unlawfully and usurpingly deprives a believer of wealth, Allah will continue to be displeased with him and does not accept his good actions that he fulfills; and none of them will be recorded among his good deeds until he repents and returns the wealth which he had taken to its owner."
Mustadrak-ul-Wasa'il, vol. 17, p. 89

Greetings
The Holy Prophet [s] said: "When you meet each other then initiate greeting (salam) and embrace; and when you separate from each other, then depart with seeking forgiveness."
Bihar-ul-Anwar, vol. 76, p. 4

Imam Husayn-ibn-Ali [a] said: "Seventy rewards is the share of the one who initiates a 'greeting' and only one reward belongs to the one who returns the 'greeting'." (When two people see each other, the initiator of the exchange of greetings receives a greater reward.)
Bihar-ul-Anwar, vol. 78, p. 120

Imam Sadiq [a] said that the Messenger of Allah [s] gathered the children of 'Abd-il-Muttallib and said: "O' children of 'Abd-il-Muttallib! Initiate greetings, have regard for kinship, perform the night prayers while people are asleep, feed (others) food, and deliver good speech and thereby you will enter paradise in peace."
Bihar-ul-Anwar, vol. 69, p. 393

Imam Sadiq [a] said: "He who initiates a greeting is more beloved with Allah and His Messenger."
Wasa'il-ush-Shiah vol.12, p. 55

Enjoining Right and Forbidding Wrong
And from among you there should be a party who invite to good and enjoin what is right and forbid the wrong, and these it is that shall be successful.
'Al-i-'lmran, No. 3, verse 104

The Holy Prophet [s] said: "The time when my Ummah (Muslim followers) merely count on others to enjoin right and forbid wrong, in fact, they have declared a fight against Allah, the Exalted."
Bihar-ul-Anwar, vol. 100, p. 92

Imam Amir ul Mu'mineen Ali [a] said: "He who abandons forbidding what is wrong theoretically and practically (and is indifferent while seeing vices committed) is a moving corpse amongst the living."
Bihar-ul-Anwar, vol. 100, p. 94

The Holy Prophet [s] said: "To prevent a Muslim from doing an unlawful action is equivalent with Allah to the performance of seventy accepted Hajj."
Mustadrak Al-Wasa'iI-ush-Shia'h, vol. 11, p. 278

Imam Amir ul Mu'mineen Ali [a] said: "Ask others to do good; you will thus be among the good doers. Desist others from evil with your action as well as your speech, and stay away, to the best of your ability, from he who commits it. Struggle for Allah as is His due; and the reviling of a reviler should not deter you in matters of Allah. Leap into danger for the sake of right wherever it may be."
Nahjul Balagha, p. 392 letter 31

Imam Baqir [a] said: "Verily, enjoining what is right and forbidding what is wrong is the way of prophets and the method of good doers. It is such a great obligatory deed (wajib) by which other obligatory deeds can survive, other creeds can be saved, bargains are lawful, injustices are warded off, and prosperity can fill the earth..."
Al-Kafi, vol. 5, p. 56

Imam Amir ul Mu'mineen Ali [a] said: "The firmness of the religion is due to enjoining what is good and forbidding what is wrong, and observing the limits of Allah.
Ghurar-ul-Hikam, p. 236

The Holy Prophet [s] said: "The one who sees a wrong action done should prohibit it by his deed, if he is capable, of course; and if he cannot do that, he should prohibit it by his tongue, but if he is not able to do even that, he may forbid it by his heart."
Wasa'il-ush-Shi'ah, vol. 16, p. 135

The Holy Prophet [s] said: "He who enjoins right and prohibits wrong is the vicegerent of both Allah and His Messenger on the earth."
Mustadrak-ul-Wasa'il, vol. 12, p. 179

The Holy Prophet [s] said: " Whensoever my Ummah undertake to enjoin right and prohibit evil and associate in establishing benevolence, they live happily and prosperously; but when they stop doing so, the blessings will be taken off from them."
At-Tahthib, vol. 6, p. 181

Imam Amir ul Mu'mineen Ali [a] said to Imam al-Hassan and Imam al-Husayn [a] when Ibn Muljam (the curse of Allah be upon him) struck him (fatally with a sword): "... Fear Allah (and again) fear Allah in the matter of Jihad, (struggle for the Holy War), with the help of your property, lives and speech in the way of Allah..."
"Do not give up bidding for good and forbidding from evil lest the mischievous gain positions over you, and then (in that case) when you pray, your invocations will not be granted to you.
Nahjul Balagha, Letter 47, p. 422

Imam Amir ul Mu'mineen Ali [a] said: "Enjoining good is the most excellent deed of people."
Mustadrak-ul-Wasa'il, vol. 12, p.185

Imam Sadiq [a] said: "All good deeds totally, including even the struggle in the Holy War in the way of Allah, comparing with enjoining right and forbidding wrong, is like a small amount of saliva compared with a deep ocean.
Bihar-ul-Anwar, vol. 100, p. 89

Imam Baqir, the fifth Imam, [a] said: " Allah, Almighty and Glorious, revealed to Prophet Jethro (Shu'ayb) [a]: 'I will punish one hundred thousand people of your folk. Forty thousand people are from their vicious ones but sixty thousand of them are from their good-doers. Jethro [a] inquired: 'These are the vicious (who deserve punishment), but what about the good-doers?' Then, Allah, Almighty and Glorious, revealed to him: 'They (the good-doers) associated with the sinners and did not become angry because of My wrath."
Al-Kafi, vol. 5, p. 56

Imam Amir-uI-Mu'mineen Ali [a] said: "Ask others to do good and forbid evil and do know that 'enjoining right and forbidding wrong' never draws death near nor ceases sustenance."
Wasa'il-ush-Shi'ah, vol. 16, p. 120
Imam Sadiq [a] said: "Woe to the people who do not support the religion of Allah by enjoining good and forbidding evil."
Mustadrak Al-Wasa'il-ush-Shi'ah, vol. 12, p. 181

Companions & Friendship
The Holy Prophet [s] said: "Man is influenced by the faith of his friends. Therefore, be careful of whom you associate with."
Bihar-ul-Anwar, vol. 74, p. 192

Imam Sadiq [a] said: "Be the friend of he who may grace you, not of one whom you are better than." (- viz. make friends with ones who are higher than you so that you progress.)
Bihar-ul-Anwar, vol. 76, p. 267

Imam Sadiq [a] said: "My most beloved brother is he who (makes me aware of) my faults."
Bihar-ul-Anwar, vol. 74, p. 282

Imam Amir-ul-Mu'mineen Ali [a] said: "Verily, there are three (types of) friends for a Muslim:
1.The friend who says: 'I am with you whether you are alive or dead', and this is his deed. 2.The friend who says: ' I am with you unto the threshold of your grave and then I will 3.The friend who says: 'I will be with you until when you die', and this is his wealth which will belong to the inheritors when he dies."

Note:
From this tradition, and the like, we understand that the only thing which will avail for individuals in the Hereafter is Faith and good deeds. This is also referred to in many Islamic traditions as well as the verses of the Holy Qur'an, for example:

"1.For those who believe and work righteousness is (every) blessedness and a beautiful place of (final) return." (13:29) "2.As to those who believe and work righteousness, verily We shall not suffer to perish the reward of any who do a (single) righteous deed." (18:30) "3.As to those who believe and work righteous deeds, they have, for their entertainment, the Gardens of Paradise." (18: 107) "4.On those who believe and work deeds of righteousness, will (God) Most Gracious bestow Love." (19:96)
Al-Khisal by Saduq, vol. 1, p. 88

Imam Sadiq [a] said: "Be careful to have truthful friends and try to obtain them, for they are your support when you are in welfare, and your advocator when you have misfortune.
Bihar-ul-Anwar, vol. 74, p. 187

Imam Sajjad [a] said: "The meeting of the righteous invites you to goodness."
Bihar-ul-Anwar, vol. 78, p.141

Imam Sajjad [a] said: "Beware of the companionship of the sinful, and helping of the unjust."
Bihar-ul-Anwar, vol. 78, p.151

Immoral Friends
Imam Sadiq [a] said: "He who seeks the company of those who insult the lovers of Allah has surely disobeyed Him, the Sublime."
Usul-i-Kafi, vol. 2, p. 379

Imam Sadiq [a] said: "When you are informed of a fellow companion committing an evil action, then go to him and tell him: 'O so and so! Either refrain from committing this sin or keep away from us'; then, avoid him unless he does so."
Wasa'il-ush-Shi'ah, vol. 16, p. 146

Imam Sadiq [a] has narrated from his father Imam Muhammad Baqir [a] who said his father Ali ibn Husayn [a] stated: "O' my son! Beware of five (groups) and do not seek companionship with them, do not speak with them, and do not make friends with them on (the) way."

Then, Imam Baqir [a] asked his father who they were and might he introduce them to him. He responded:

"1.Beware of and do not associate with the one who tells lies. He is as a mirage which makes near for you what is far, and makes far to you what is near." "2.Beware of and do not associate with an immoral person, because he will sell you at the price of a morsel or less than that." "3.Beware of and do not associate with a miser because he will deprive you of his wealth when you are seriously in need of it." "4.Beware of and do not associate with a fool, because he wants to be of avail to you but he harms you." "5.Beware of and do not associate with the one who disregards his kinfolks, because I found him (such a person) cursed in the Book Allah, Almighty and Glorious, in three occurrences."
They are: (Sura AI-Baqarah, No.2, verse 27; Sura Ar-Ra'd, No.13, verse 25; and Sura Muhammad, No.47, verse 22).
Al-Kafi, vol. 2, p. 641

Imam Amir-ul-Mu'mineen Ali [a] said: "O' Kumayl! Say what is just in any condition. Be friends with the righteous and avoid the evil doers, stay away from the hypocrites and do not accompany the treacherous."
Mustadrak-ul-Wasa'il, vol. 12, p. 197

Serving People
The Holy Prophet [s] said: "He who decreases a grief out of the grieves of this world for his Muslim brother, Allah will decrease for him a grief out of the grieves of the Hereafter."
Shahab-ul-Akhbar, p. 194

Imam Husayn [a] said: "Verily, the procession of people's needs towards you is from among the blessings of Allah upon you. Therefore, grieve ye not because of these blessings."
Bihar-ul-Anwar, vol. 74, p. 318

Imam Amir ul Mu'mineen Ali [a] said: "Whenever you find that your Muslim brother is in need, try to see to it." (Do not let him feel compelled to verbalize his need).
Bihar-ul-Anwar, vol. 74, p. 166

Imam Sadiq [a] narrates from his forefathers [a], from the Messenger of Allah [s], who said: "He who feeds a believer to satiate him, Allah will feed him from the fruits of Heaven; he who dresses him to cover his nakedness, Allah will give him clothing of brocade and silk; he who quenches the thirst of a believer, Allah will give him drink of the sealed container; and he who helps him or removes his grief, Allah will settle him under the shade of His Throne on the Day of Reckoning when there is no shade except for His Shade."
Bihar-ul-Anwar, vol. 74, p. 382

The Holy Prophet [s] said: "People are the dependents of Allah for sustenance, so the most beloved one of people with Him is the one who is helpful to the dependents Allah and makes the family members of a house happy."
AI-Kafi, vol. 2, p. 164

The holy Prophet [s] said: "He who helps a Muslim believer (in his troubles), Allah, Almighty and Glorious, will remove from him seventy-three agonies, one of which is in this world and seventy-two other agonies at the time of Great Agony, when people are busy with themselves (in Hereafter)."
Al-Kafi, vol. 2, p.199