Delayed Payment in selling Gold
Question :
What is the ruling on whoever buys some gold and he still has a balance to pay on its price and he says, "I will bring it to you when I am able."?
Answer:
This transaction is not permissible. If the person did so, the sales agreement is correct regarding what the merchant took for it and it is invalid regarding what he did not take (i.e., the unpaid balance). This is because the Prophet said regarding selling gold and silver:
"Sell however you wish, as long as it is hand to hand."
Source:
Ash-Shaykh Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 4 Pages 408-409