That Abu Bakr wrote for him, Zakat regulations which Messenger of Allah ﷺ had made compulsory, and wrote that one should neither collect various portions (of the property) nor divide the property into various portions in order to avoid paying Zakat.
أَنَّ أَبَا بَكْرٍ كَتَبَ لَهُ فَرِيضَةَ الصَّدَقَةِ الَّتِي فَرَضَ رَسُولُ اللَّهِ ﷺ وَلاَ يُجْمَعُ بَيْنَ مُتَفَرِّقٍ وَلاَ يُفَرَّقُ بَيْنَ مُجْتَمِعٍ خَشْيَةَ الصَّدَقَةِ
Abu Bakr wrote to me what was made compulsory by Messenger of Allah ﷺ and that was (regarding the payments of Zakat): Neither the property of different people may be taken together nor the joint property may be split for fear of (paying more, or receiving less) Zakat.
أَنَّ أَبَا بَكْرٍ ؓ كَتَبَ لَهُ الَّتِي فَرَضَ رَسُولُ اللَّهِ ﷺ وَلاَ يُجْمَعُ بَيْنَ مُتَفَرِّقٍ وَلاَ يُفَرَّقُ بَيْنَ مُجْتَمِعٍ خَشْيَةَ الصَّدَقَةِ
Suwaid bin Ghaflah reported The collector of the Prophet ﷺ came to us. I caught hold of his hand and read in the document that the goods were not to be combined nor were they to be separated for fear of zakat. There is no mention of milch animals in this tradition. (Using translation from Abū Dāʾūd 1580)
أَتَانَا مُصَدِّقُ النَّبِيِّ ﷺ فَأَخَذْتُ بِيَدِهِ فَقَرَأْتُ فِي عَهْدِهِ «أَنْ لَا يُجْمَعَ بَيْنَ مُتَفَرِّقٍ وَلَا يُفَرَّقَ بَيْنَ مُجْتَمِعٍ خَشْيَةَ الصَّدَقَةِ»