What is the ruling on gold purchased by a person online, which reached him several days later, after he had paid its full price, and he was unaware of the necessity of hand-to-hand possession?

If someone was unaware of the prohibition against not taking possession of gold immediately upon purchase, there is no harm in them benefiting from what they bought, and they are not sinful if they cease this practice as soon as they become aware of it. This is based on the Almighty's saying: "So whoever receives an admonition from his Lord and stops, then he may keep what is past, and his affair is for Allah." As for purchasing gold online, the buyer can delegate someone to take possession of the gold on their behalf at the same time as the contract, and the price can be paid via credit cards or bank transfers, which achieves constructive possession.