Sahih Muslim
The Book of Zakat (Kitab Al-Zakat)
Book Number: 005 / Hadith Number: 2189
A hadith like this has been narrated on the authority of Zainab the wife of 'Abdullah, and she said: I was in the mosque and the Prophet of Allah (may peace be upon him) saw me and said: Give Sadaqa even though it is out of your jewellery. The rest of the hadith is the same.