Infallible pieces of advice

Imam Ali’s (as) advice to his sons

"O my son, learn four things and (a further) four things from me. Nothing will harm you if you practise them.
1. That the richest of riches is intelligence;
2. The biggest destitution is foolishness;
3. The wildest wildness is vanity and
4. The best achievement is goodness of moral character.

"O' my son, you should avoid making friends with:
1. a fool because he may intend to benefit you but may harm you
2. a stingy person because he will run away from you when you need him most
3. a sinful person because he will sell you for nothing
4. a liar as he is like a mirage, making you feel far things near & near things far.”