Al-Kāfi - Volume 3 > Times Zakat Is Due
Hadith #3

3ـ مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنِ الْحَسَنِ بْنِ عَلِيٍّ عَنْ يُونُسَ بْنِ يَعْقُوبَ قَالَ قُلْتُ لأَبِي عَبْدِ الله (عَلَيْهِ الْسَّلام) زَكَاتِي تَحِلُّ عَلَيَّ فِي شَهْرٍ أَ يَصْلُحُ لِي أَنْ أَحْبِسَ مِنْهَا شَيْئاً مَخَافَةَ أَنْ يَجِيئَنِي مَنْ يَسْأَلُنِي فَقَالَ إِذَا حَالَ الْحَوْلُ فَأَخْرِجْهَا مِنْ مَالِكَ لاَ تَخْلُطْهَا بِشَيْ‏ءٍ ثُمَّ أَعْطِهَا كَيْفَ شِئْتَ قَالَ قُلْتُ فَإِنْ أَنَا كَتَبْتُهَا وَأَثْبَتُّهَا يَسْتَقِيمُ لِي قَالَ لاَ يَضُرُّكَ.

3. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from al-Hassan ibn Ali from Yunus ibn Ya’qub who has said the following: “I once said to abu ‘Abd Allah, ‘Alayhi al-Salam, that there is a certain month in which I pay Zakat. Can I keep a certain amount separate for an emergency, in case, someone comes asking? He (the Imam) said, ‘Once the year is complete, you must pay Zakat of your asset and you must not mix it with anything, and then give whatever you want.’ I then asked, ’Can I write it down and keep a record to make it straight? He (the Imam) said, ‘That is not harmful.’”