Sayyiduna Zayd bin Thabit (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) permitted the owner of the 'ariyyah to sell the dates by estimation.
(b) In the narration of Imam al-Shafi'i (may Allah have mercy on him) and al-Qa'nabi (may Allah have mercy on him): he (peace and blessings be upon him) permitted the owner of the 'ariyyah to sell it by estimation.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10650