Al-Imaam Ahmad Ibn Hanbal said:
Az-Zuhd is of three types:
The first: abandoning that which is haraam (forbidden) – and it is the zuhd of the general folk.
The second: abandoning the excesses of that which is halaal (lawful) – and it is the zuhd of the people of distinction.
The third: abandoning that which busies one from Allaah – and it is the zuhd of the acquainted ones.
Imaam Ahmad Ibn Hanbal
Jaami’ al-aadaab vol 1 page 372-373
Translated by Aboo Haatim Muhammad Farooq
[Note: Az-Zuhd means Asceticism. However this is not the asceticism that is commonly attributes to the sect of the Sufis. Rather it is a practise by the most righteous of people and it is to renounce worldly pleasures in order to get closer to Allaah. It should not be understood that Az-Zuhd means to sell all worldly materials and then beg to the people as this is not an act of those who fear Allaah, but an act of the ignorant.]