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 leave you', and this is his child.
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

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