Answer
(Fatwa: 1161/D=250/File D=1432)
After completing the purchase of gold and paying its price to the seller, if you took the slip instead of gold then your gold was due on the seller and in future, you can take it by producing the slip wherever you wish. In this case, if you say to the seller instead of taking the gold in your possession that now the rate is increased, so sell it on my behalf so that I could get the price with benefit. In this case, too, the selling took place before taking possession and the possession of you (buyer) on the gold was not complete, hence selling it before taking it in your possession or asking the dealer for selling is not lawful. Hadith forbids from selling any item before taking it in one’s possession.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband