Sahih Bukhari Volume 001, Book 003, Hadith Number 097B.
Narated By Ibn 'Abbas : Once Allah's Apostle came out while Bilal was accompanying him. He went towards the women thinking that they had not heard him (i.e. his sermon). So he preached them and ordered them to pay alms. (Hearing that) the women started giving alms; some donated their ear-rings, some gave their rings and Bilal was collecting them in the corner of his garment.