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

Hadith n. 71
71. Amir al-mu’minin, peace be upon him, said: As intelligence increases, speech decreases.

Hadith n. 72
72. Amir al-mu’minin, peace be upon him, said: Time wears our bodies, renews desires, brings death nearer and takes away aspirations. Whoever is successful with it encounters grief and whoever misses its favours also undergoes hardships.

Hadith n. 73
73. Amir al-mu’minin, peace be upon him, said: Whoever places himself as a leader of the people should commence with educating his own self before educating others; and his teaching should be by his own conduct before teaching by the tongue.

The person who teaches and instructs his own self is more entitled to esteem then he who teaches and instructs others.

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