Sahih Al Bukhari Hadith Number 1412

Narrated Abu Huraira: The Prophet (peace be upon him) said, “The Hour (Day of Judgment) will not be established till your wealth increases so much so that one will be worried, for no one will accept his Zakat and the person to whom he will give it will reply, ‘I am not in need of it.’ “

24  Obligatory Charity Tax (Zakat)
Hadith number 1412
Volume no 2
Chapter: 9 (To practise charity before such time when nobody would accept it)