The six substances (items) that are sold by weight and measure, literally: gold, silver, dates, wheat, salt and barley. Exchanging these substances in kind must be in equal measure and with immediate transfer of possession (qabdh) in order to avoid exchanging unequal amounts (measures and weights) or the so called riba in trade (riba al-fadhl). If carried out in conformity to these conditions, then the exchange is riba-free (i.e., halal/ permissible/ shari’a compliant).