Hadith 518370
Chapter 58: Sadaqa - كتاب الصدقة
حَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " لاَ تَحِلُّ الصَّدَقَةُ لآلِ مُحَمَّدٍ إِنَّمَا هِيَ أَوْسَاخُ النَّاسِ " .
Yahya related to me from Malik that he heard that the Messenger of Allah, may Allah bless him and grant him peace, said, "Sadaqa to the family of Muhammad is not halal. It is only people's impurities."
Reference Muwatta Malik 518370
USC-MSA web (English) reference : Book 58, Hadith 13