Maliks Muwatta Book 17, Hadith Number 10.

Section : Things on Which there is No Zakat, in the Way of Jewellery, Bits of Gold and Silver, and Amber.

Yahya related to me from Malik from Abd ar-Rahman ibn al-Qasim from his father that A’isha, the wife of the Prophet, may Allah bless him and grant him peace, used to look after the orphaned daughters of her brother in her house. They had jewellery (which they wore) and she did not take zakat from this jewellery of theirs.