Sahih Muslim Book 5, Hadith Number 2208.

Chapter : Acceptance of Sadaqa by honest work and its growth.

Abu Huraira reported Allah’s Messenger (way peace be upon him) as saying: The Last Hour will not come before wealth becomes abundant and overflowing, so much so that a man takes Zakat out of his property and cannot find anyone to accept it from him and till the land of Arabia becomes meadows and rivers.