Al-Imam Ali (p.b.u.h), said:

Hadith n. 438

438. Amir al-mu’minin, peace be upon him, said: People are enemies of what they do not know.

Hadith n. 439

439. Amir al-mu’minin, peace be upon him, said: The whole of asceticism is confined between two expressions of the Quran. Allah, the Glorified says:

Lest distress you yourselves for what escapes you, and be overjoyous for what He has granted you (Quran, 57:23).

Whoever does not grieve over what he misses and does not revel over what comes to him acquires asceticism from both its sides.

Hadith n. 440

440. Amir al-mu’minin, peace be upon him, said: What a breaker is sleep for resolutions of the day!

Hadith n. 441

441. Amir al-mu’minin, peace be upon him, said: Governing power is the proving ground for people.

Hadith n. 442

442. Amir al-mu’minin, peace be upon him, said: No town has greater right on you than the other. The best town for you is that which bears you.

Hadith n. 443

443. When the news of the death of (Malik) al-Ashtar (may Allah have mercy on him), reached Amir al-mu’minin, peace be upon him, he said: Malik, what a man Malik was! By Allah, if he had been a mountain he would have been a great one (find), and if he had been a stone he would have been hard; no horseman could have reached it and no bird could have flown over it.

Source: https://www.al-islam.org/nahjul-balagha-part-2-letters-and-sayings