Any sale in which the sold item cannot be delivered, or its measure or weight is unspecified, is invalid as per the laws of Islam. The Prophet ﷺ forbade some forms of sales that fit this profile, including the one mentioned in this hadeeth. The Taabi’ee (a Muslim who saw at least one of the Companions)Aboo Al-Bakhtari At-Taa’ee narrated that he asked ‘Abbaas (may Allah be pleased with them) about the Salam transaction for dates. Salam transaction (i.e., a sale of payment in advance) refers to a sales transaction whereby a buyer purchases a clearly defined item to be delivered at a fixed future date, and pays its price in advance, in the contracting session. Ibn ‘Abbaas (may Allah be pleased with him) replied "The Prophet ﷺ forbade the sale of unpicked dates till they became (ripe and) ready for consumption,” meaning that dates may not be sold except after they become ripe and edible, “and could be weighed.” A man asked what was to be weighed (as the dates were still on the trees). It is not possible to know the measure of unpicked dates! Another man sitting beside Ibn ‘Abbaas (may Allah be pleased with them) replied, “(It rather means) Till they are cut and stored.” Another version of the hadeeth reads: “… after their measure/weight is estimated,” meaning without plucking them. This helps with regard to knowing the amount of the due Zakaah payable to the poor before the owner disposes of the dates, and knowing the quantity that will be sold, so that there should be no ambiguity of the sold item, nor Gharra (i.e., risk and uncertainty) regarding its value. The one who estimates the measure/weight of the fruits on the trees is called Khaaris (estimator). .