What is Zuhd? Sh. Uthaymeen

Shaykh ibnu Uthaymeen said:
The people of knowledge said that zuhd (asceticism) is leaving off that which does not benefit a persons’ hereafter, in the sense that a person abstains from things that are allowed (permissible) if it is not going to benefit them in the hereafter.
And from the things that aids upon this Zuhd is that a person contemplates about this worldly life and realises that it is a temporary dwelling and not a permanent dwelling; it has not remained for anyone before you so if it did not remain for anyone who preceded you then it will not stay for you.
Allah says: {And We granted not to any human being immortality before you, then if you die, would they live forever?} [Al-Anbiyaa #34]
Meaning; no one has ever lived forever in this world. By this a person comes to know that this world is a dwelling where there is disorder, in that what makes a person happy today may sadden him tomorrow. So when a person comes to know the reality of this world, with his intelligence and eemaan he will abstain from indulging in it and he will not prefer it over the Hereafter.
Allah says: {But, you prefer the life of this world-Although the Hereafter is better and more lasting-Verily! This is in the former Scriptures-The Scriptures of Ibrahim (Abraham) and Musa (Moses)} [Al-Alaa # 16-19]
Fataawaa Noor Alaa Ad-Darb #14