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

Hadith n. 84
Amir al-mu’minin, peace be upon him, said: The survivors of the sword (from getting killed) are large in number and have a large progeny.

Hadith n. 85
Amir al-mu’minin, peace be upon him, said: Whoever abandons saying, “I do not know” meets his destruction.

Hadith n. 86
Amir al-mu’minin, peace be upon him, said: I love the opinion of an old man more than the determination of a young man; (or according to another version) more than the martyrdom of a young man.

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