The Holy Prophet [s] said: "The most (important ) things that cause people to reach Heaven are divine piety and a good temper."
Bihar-ul-Anwar, vol. 71, p. 373
The Holy Prophet [s] advised: "When making a decision to do something, think about its outcome. If it is good for your advancement and development, follow it, but if it is misleading, leave it out...."
Bihar-ul-Anwar, vol. 77, p. 130
Imam Sadiq [a] was asked about the meaning of 'piety' when he replied: "Piety is that Allah does not miss you in the place where He has commanded you to be, and does not see (find) you where He has forbidden you from."
Safinat-ul-Bihar, vol. 2, p. 678
The Holy Prophet [s] said: "Show veneration for Allah similar to the way that you would mind your manners in front of a righteous person among your kinsmen."
Mustadrak Al-Wasa'il-ush Shi'ah, vol. 8, p. 466, No.10027
Imam Amir-ul-Mu'mineen Ali [a] said: "Lowering one's eyes will serve well as a barrier against one's passions."
Ghurar-ul-Hikam, p. 321
Imam Amir ul Mu'mineen Ali [a] said to Imam al-Hassan and Imam al-Husayn (peace be upon them) when 'Abd-ur-Rahman ibn Muljam (the curse of Allah be upon him) had struck him (fatally with a sword):
"I advise you (both) to fear Allah and that you should not hanker after the (pleasures of this) world even though it may run after you. Do not be sorry for anything of this world that you have been denied. Speak the truth and act (in expectation) for reward. Be an enemy of the oppressor and helper of the oppressed."
Nahj-ul-Balagha, letter 47
Imam Amir ul Mu'mineen Ali [a] said: "I advise you to fear Allah, 'O my child, to abide by His commands, to fill your heart with remembrance of Him and to cling to hope in Him. No connection is more reliable than the connection between you and Allah provided you take hold of it."
Nahj-ul-Balagha, letter 31
Abi-Osamah said that he had heard that Imam Sadiq [a] said: "Be aware of (the punishment of) Allah, piety, godly endeavor, saying the truth, honesty in deposition, good character, and good neighbourliness. Invite (others) to yourselves (by performing good actions), not with mere utterance. Live to be ornaments, and not to be a disgrace to us. (I advise you) to prolong the length of bowing and prostration. So, verily, when one of you prolongs bowing and prostration, Satan cries from behind one and says: Woe! He obeyed and I disobeyed; he did prostration and I refused."
Al-Kafi, vol. 2, p. 77
Imam Ali ibn Husayn [a] said: "Behold! Verily, on the friends of Allah there will be no fear nor shall they grieve if they keep up the obligatories of Allah, follow the traditions of the Messenger Allah [s], avoid the things forbidden by Allah, be pious in worldly wealth and rank and eager for what there is with Allah, strive to earn His sustenance of what is pure, and decide not to boast or compile wealth but donate and give the obligatory alms they have been enjoined to. Hence, these are those (friends of Allah!) whose earnings are divinely blessed and will be rewarded for what they have sent forth unto their next world."
Bihar-ul-Anwar, vol. 69, p. 277
The Holy Prophet [s] said: "Surely, human beings from the time of Adam up to now are the same as the teeth of a comb are, and there is no superiority for the Arab over non-Arab or for the red race over the black race except for piety."
Imam Sadiq [a] said: "Surely, a little action (of worshipping) with piety is better than many deeds with no virtue."
Al-Kafi, vol. 2, p. 76