Abu Amr al-Awza'i (may Allah have mercy on him) relates that Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) would send (the estimators) and say: "Make it easy for them, for among (the produce) there is the 'ariyyah, the wati'ah and the akilah."
Al-Walid says: I said to Abu Amr: What is the 'ariyyah? He said: "One, two or three date palms which a man gives to a needy man." Then I said: What is the akilah? He said: "The owners of the property who eat fresh dates from it; that is not to be estimated, and it is deducted from its estimate." I said: What is the wati'ah? He said: "Those who visit them and call on them."
This wording about lightening (the estimate), which al-Awza'i narrated from Umar (may Allah be pleased with him), has been narrated by Makhul from the Prophet (peace and blessings be upon him) in mursal form, and a musnad hadith has been narrated on this with a chain that is not strong.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7447