Fiqh-us-Sunnah Volume 3, Zakaat and Fasting, Fiqh 3.102B.

For one who is fit and capable of earning his living, giving sadaqah of all his property is permissible.

‘Umar reports: “The Messenger of Allah, upon whom be peace, instructed us to give sadaqah, and it applied to my property. I said: ‘Today I shall better Abu Bakr. I have never bettered him.’ Then I brought half my property. The Messenger of Allah, upon whom be peace, said: ‘What did you leave for your family?’ I said: ‘An amount like this.’ Abu Bakr came with all his property, and the Messenger of Allah, upon whom be peace, asked: ‘What did you leave for your family?’ He said: ‘I have left Allah and His Messenger, upon whom be peace, for them.’ Then I said: ‘I shall never better you in anything.'” This is related by Abu Dawud and atTirmizhi. The latter grades it authentic.