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

Hadith n. 36

Amir al-mu’minin, peace be upon him, said: Whoever prolongs his desire ruins his actions.

Hadith n. 37

Once Amir al-mu’minin, peace be upon him, was proceeding towards Syria when the countrymen of al-Anbar met him. Seeing him they began to walk on foot and then ran in front of him. He enquired why they were doing so and they replied that this was the way they respected their chiefs. Then he said:

By Allah, this does not benefit your chiefs. You are belabouring yourself in this world and earning misery for the next world by it. How harmful is the labour in whose wake there is punishment and how profitable is the case with which there is deliverance from the Fire (of Hell).

Hadith n. 38

Amir al-mu’minin, peace be upon him, said to his son al-Hasan:

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

O my son, you should avoid making friends with a fool because he may intend to benefit you but may harm you; you should avoid making friends with a miser because he will run away from you when you need him most; you should avoid making friends with a sinful person because he will sell you for nought; and you should avoid making friends with a liar because he is like a mirage, making you feel far things near and near things far.

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