nahj al balagha

He has opened for you the door of repentance; therefore, whenever you call Him, He hears your call, and whenever you whisper to Him, He knows the whisper. Place before Him your needs, unveil yourself before Him, complain to Him of your worries, beseech Him to remove your troubles, seek His help in your affairs, and ask from the treasuries of His mercy that which no one else has power to give, namely length of life, health of body, and increase in sustenance. He has placed the keys of His treasuries in your hands in the sense that He has shown you the way to ask Him. Therefore, wherever you wish, open the doors of His favour with prayer, and let abundant rains of His mercy fall on you.
—  Imam Ali (a), Nahj al-Balagha, Letter 31
God tests His worshippers with many different hardships, He makes them engage in different struggles, and He makes them undergo multiple misfortunes. All this in order to extract arrogance from their hearts, to establish humbleness in their selves.
—  Imam Ali (as) [Nahj Al-Balagha p. 294]
By means of the Holy Qur’an, heal the sickness of your hearts and strengthen yourself through it while confronting hardships.
—  Imam Ali (a), Nahj al-Balagha, Sermon-176

“O My God! You know me better than myself, and I know myself better than they do. O My God! Make us better than what they think and forgive us what they do not know”
—Imam Ali ibn Abi Talib (عليه السلام), [Nahj Al-Balagha, saying 100]

People of ma’arifat (recognition) see that the worldly people are more concerned about physical death. While more serious is the death of their hearts within their living bodies.
—  Imam Ali (a), Nahj al-Balagha, Sermon 259
Learn the Qur’an for it is the best of narrations, and understand it thoroughly for it is the best blossoming of the hearts. Seek cure with its Light for it is the cure of the hearts. Recite it beautifully for it is the most beneficial of narrations.
—  Imam Ali (‘a), Nahj al-Balagha, Sermon 110

ـ الإمامُ عليٌّ (عَلَيهِ الّسَلامُ) ـ من وصيَّتِهِ لابنِهِ الحسنِ (عَلَيهِ الّسَلامُ) ـ: اُوصِيكَ بتَقوَى اللّه‏ِ ـ أي بُنَيَّ ـ ولُزومِ أمرِهِ، وعِمارَةِ قَلبِكَ بذِكرِهِ.

‪Imam Ali (AS), in his will to his son Imam al-Hasan (AS) said, ‘I advise you to be Godwary, O my son, and to abide by His orders, and to keep your heart alive with His remembrance.’

—  [Nahj al-Balagha, Letter 31]
“God tests His worshippers with many different hardships, He makes them engage in different struggles, and He makes them undergo multiple misfortunes. All this in order to extract arrogance from their hearts, to establish humbleness in their selves.”
Imam Ali (as) [Nahj Al-Balagha p. 294]
—  Imam Ali (as) [Nahj Al-Balagha p. 294]
The true right of the Qur'an cannot be given without making it the axis of the sociopolitical lives of the Muslims. Evidently, kissing and paying respect to a doctor’s medical prescription and reading it in a melodious tone without understanding and abiding with its recommendations and instructions can never cure the disease of a patient. Every rational person believes that recovery lies in following the instructions of a medical prescription. The real form of respect to a medical prescription is to act upon it and not to offer outward respect [only] to the doctor and his prescription.
— 

Ayatullah Mohammad Taqi Misbah Yazdi

The Quran as reflected in Nahj al Balagha p.30

“The fighter who is martyred in the way of Allah has no greater reward than the one who is able to sate himself but remains chaste. The chaste person may well become one of the angels.“

— Imam Ali ibn Abi Talib (ع) Nahj al-Balagha, Saying 474

Learn the Qur’an for it is the best of narrations, and understand it thoroughly for it is the best blossoming of the hearts. Seek cure with it’s light for it is the cure of the hearts. Recite it beautifully for it is the most beneficial of narrations.
—  Imam Ali (a), Nahj al-Balagha, Sermon 110
Be careful and do not pray to the Lord, saying, “Lord! I pray to You to protect and guard me from temptations and trials”, for there is none who is not tempted and tried. But beseech Him to guard you against such temptation as may lead you towards wickedness and sins…
—  Imam Ali (a), Nahj al-Balagha, Saying #93
God (swt), described by Imam Ali(a.s):

Everything that is known through itself has been created, and everything that exists by virtue of other things is the effect (of a cause). He works but not with the help of instruments. He fixes measures but not with the activity of thinking. He is rich by not by acquisition. Times do not keep company with Him, and implements do not help Him. His Being precedes times. His existence precedes non-existence and His eternity precedes beginning. By His creating the senses it is known that He has no senses. By the contraries in various matters it is known that He has no contrary, and by the similarity between things it is known that there is nothing similar to Him. He has made light the contrary of darkness, brightness that of gloom, dryness that of moisture and heat that of cold. He produces affection amongst inimical things. He fuses together diverse things, brings near remote things and separates things which are joined together. He is not confined by limits nor counted by numbers. Stillness and motion do not occur in Him and how can that occur in Him which He has Himself made to occur and how can a thing revert to Him which He first created and how can a thing appear in Him which He first brought to appearance. If it had not been so, His self would have become subject to diversity, His being would have become divisible (into parts) and His reality would have been prevented from being deemed Eternal. If there was a front to Him there would have been a rear also for Him. He would need completing only if shortage befell Him. In that case signs of the created would appear in Him, and He would become a sign (leading to other objects) instead of signs leading to Him. Through the might of His abstention (from affectedness) He is far above being affected by things which affect others. He is that which does not change or vanish. The process of setting does not behove Him. He has not begotten anyone lest He be regarded as having been born. He has not been begotten otherwise He would be contained within limits. He is One, but not by counting. He is everlasting without any limit. He is existent without any support. Minds admit of Him without (any activity of the senses). Things which can be seen stand witness to Him without confronting Him. Imagination cannot encompass Him. 

- Extracts from Sermons 185 and 186 by Ali Ibn Abi Taleb (a.s) from Nahj Al Balagha (’The Peak of Eloquence’) compiled by Allamah ash-Sharif ar-Radi.