Narrated Aisha, Ummul Mu'minin:

The Prophet (ﷺ) used to send Abdullah ibn Rawahah (to Khaybar), and he would assess the amount of dates when they began to ripen before they were eaten (by the Jews). He would then give choice to the Jews that they have them (on their possession) by that assessment or could assign to them (Muslims) by that assignment, so that the (amount of) zakat could be calculated before the fruit became eatable and distributed (among the people).

حَدَّثَنَا يَحْيَى بْنُ مَعِينٍ، حَدَّثَنَا حَجَّاجٌ، عَنِ ابْنِ جُرَيْجٍ، قَالَ أُخْبِرْتُ عَنِ ابْنِ شِهَابٍ، عَنْ عُرْوَةَ، عَنْ عَائِشَةَ، - رضى الله عنها - قَالَتْ كَانَ النَّبِيُّ صلى الله عليه وسلم يَبْعَثُ عَبْدَ اللَّهِ بْنَ رَوَاحَةَ فَيَخْرُصُ النَّخْلَ حِينَ يَطِيبُ قَبْلَ أَنْ يُؤْكَلَ مِنْهُ ثُمَّ يُخَيِّرُ يَهُودَ يَأْخُذُونَهُ بِذَلِكَ الْخَرْصِ أَوْ يَدْفَعُونَهُ إِلَيْهِمْ بِذَلِكَ الْخَرْصِ لِكَىْ تُحْصَى الزَّكَاةُ قَبْلَ أَنْ تُؤْكَلَ الثِّمَارُ وَتُفَرَّقَ ‏.‏