Abu Dharr (radiyAllahu ’anhu) reported:
The Messenger of Allah (sallAllahu ‘alayhi wa sallam) said, “O Aba Dharr, do you say an abundance of possessions is wealth?”
I said yes.
The Prophet said, “Do you say a lack of possessions is poverty?”
I said yes.
The Prophet repeated this three times, then he (sallAllahu ‘alayhi wa sallam) said,
Wealth is in the heart and poverty is in the heart.
Whoever is wealthy in his heart will not be harmed no matter what happens in the world.
Whoever is impoverished in his heart will not be satisfied no matter how much he has in the world.
Verily, he will only be harmed by the greed of his own soul.
[al-Mu’jam al-Kabir 2/154, Grade: Sahih (authentic) according to al-Albani (rahimahullah)]