Imam Sadiq (A.S.) 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.S.) 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 Amir-ul-Mu'mineen Ali (A.S.) 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
The Holy Prophet (A.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.S.) 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.S.) 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.S.) narrates from his forefathers [a], from the Messenger of Allah (peace be upon him and his household), 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 (peace be upon him and his household) 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 (peace be upon him and his household) 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
* Source: alhassanain.com