Hadith 510710
Chapter 26: The 'Aqiqa - كتاب العقيقة
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ جَعْفَرِ بْنِ مُحَمَّدٍ، عَنْ أَبِيهِ، أَنَّهُ قَالَ وَزَنَتْ فَاطِمَةُ بِنْتُ رَسُولِ اللَّهِ صلى الله عليه وسلم شَعَرَ حَسَنٍ وَحُسَيْنٍ وَزَيْنَبَ وَأُمِّ كُلْثُومٍ فَتَصَدَّقَتْ بِزِنَةِ ذَلِكَ فِضَّةً .
Yahya related to me from Malik from Jafar ibn Muhammad that his father said, "Fatima, the daughter of the Messenger of Allah, may Allah bless him and grant him peace, weighed the hair of Hasan, Husayn, Zaynab and Umm Kulthum, and gave away in sadaqa an equivalent weight of silver."
Reference Muwatta Malik 510710
USC-MSA web (English) reference : Book 26, Hadith 2