Malik b. Aus b. al-Hadathan reported: I came saying who was prepared to exchange dirhams (for my gold), whereupon Talha b. Ubaidullah (pbuh) (as he was sitting with 'Umar b. Khattib) said: Show us your gold and then come to us (at a later time). When our servant would come we would give you your silver (dirhams due to you). Thereupon 'Umar b. alKhattib (pbuh) said: Not at all. By Allah, either give him his silver (coins) or return his gold to him, for Allah's Messenger (SAW) said: Exchange of silver for gold (has an element of) interest in it. Except when (it is exchanged) on the spot; and wheat for wheat is an interest unless both are handed over on the spot: barley for barley is interest unless both are handed over on the spot; dates for dates is interest unless both are handed over on the Spot. a. By referring to the hadith, elucidate the business transaction model as proposed by Prophet SAW.