Is it necessary for the Imam to send an assessor (Sa'i) to estimate the yield (Kharṣ) of fruits when they begin to ripen?

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The Imam must send an assessor when the fruits begin to show signs of ripeness to estimate their yield and determine the amount of Zakat owed, making the owner aware of this assessment. This practice was held by Umar ibn al-Khattab, Sahl ibn Abi Hathmah, Marwan, Al-Qasim ibn Muhammad, Al-Hasan, 'Ata', Al-Zuhri, 'Amr ibn Dinar, 'Abd al-Karim ibn Abi al-Makhariq, Malik, Al-Shafi'i, Abu 'Ubayd, and Abu Thawr, and the majority of scholars. The evidence supporting this is the report that the Prophet, peace be upon him, used to send people to assess their vineyards and fruits. Furthermore, he commanded that grapes be estimated (kharṣ) just as dates from palm trees are estimated, and Zakat should be taken from the grapes as raisins just as it is taken from the palm trees as dates. The Prophet, peace be upon him, acted upon this by assessing the garden of a woman in Wadi al-Qura, and Abu Bakr and the Caliphs acted upon it thereafter. The time for this assessment is when the fruit shows signs of ripeness, because the benefit of the estimation is to ascertain the Zakat due and permit the owners to dispose of their fruits, which necessity arises when ripeness appears and Zakat becomes obligatory.