What is the ruling of Islamic law on purchasing electrical appliances in installments from a person who first bought them for 7540 Saudi Riyals, then sold them to me for 9400 Saudi Riyals on a deferred payment basis, knowing that I do not possess the immediate price for them?

If the seller acquires the goods and takes possession of them, then sells them to you for a known, installment price, there is no harm. However, selling to you before he possesses them is not permissible. If he buys them and takes possession of them in his house, or the market, or a place to which they are transported from the seller’s ownership, then sells these items to you for a known, installment price, there is no harm.