مُوَطَّأُ مَالِكٍ
Muwatta Malik 596
Zakat
حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنِ السَّائِبِ بْنِ يَزِيدَ، أَنَّ عُثْمَانَ بْنَ عَفَّانَ، كَانَ يَقُولُ هَذَا شَهْرُ زَكَاتِكُمْ فَمَنْ كَانَ عَلَيْهِ دَيْنٌ فَلْيُؤَدِّ دَيْنَهُ حَتَّى تَحْصُلَ أَمْوَالُكُمْ فَتُؤَدُّونَ مِنْهُ الزَّكَاةَ .
Yahya related to me from Malik from Ibn Shihab from as-Sa'ib ibn Yazid that Uthman ibn Affan used to say, "This is the month for you to pay your zakat. If you have any debts then pay them off so that you can sort out your wealth and take the zakat from it."
Arabic/English book reference: Book 17, Hadith 17