The individual property of different people should neither be gathered together nor the joint property should be divided, in assessing the Zakat

Sahih al-Bukhari · Book 24 · Hadith 1450

حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ الأَنْصَارِيُّ، قَالَ حَدَّثَنِي أَبِي قَالَ، حَدَّثَنِي ثُمَامَةُ، أَنَّ أَنَسًا ـ رضى الله عنه ـ حَدَّثَهُ أَنَّ أَبَا بَكْرٍ ـ رضى الله عنه ـ كَتَبَ لَهُ الَّتِي فَرَضَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ وَلاَ يُجْمَعُ بَيْنَ مُتَفَرِّقٍ، وَلاَ يُفَرَّقُ بَيْنَ مُجْتَمِعٍ، خَشْيَةَ الصَّدَقَةِ ‏"‏‏.‏

Narrated Anas: Abu Bakr wrote to me what was made compulsory by Allah's Messenger (ﷺ) and that was (regarding the payments of Zakat): Neither the property of different people may be taken together nor the joint property…