It has been narrated from Imam Hussain (a.s.):

You will recognize Mahdi by his calmness, dignity, knowledge of the lawful and the unlawful, and the need of everyone for him and his lack of need for others.

It has been narrated from Imam Sadiq (a.s.):

By God! His clothes are nothing but rough cloth and his food is nothing but simple food.

It has been narrated from Imam Reza (a.s.):

He is the most knowledgeable of people, the wisest of people, the most pious of people, the most generous of people, and the most devout of people.

The author of the book Bishara al-Mustafa narrates from Laith ibn Tawas that:

Mahdi is a generous person who gives wealth in abundance, is very strict with his officials and government officials, and is very kind and compassionate to the poor.

(Book of the Sun of Mehr)